EMLA
Questions & Answers about EMLA
1. Drug interactions
The Core Data Sheet (CDS) states that:
4.5 Interactions
Prilocaine in high doses may cause an increase in the methaemoglobin level particularly in conjunction with methaemoglobin-inducing agents (e.g. sulphonamides).
With large doses of EMLA (Cream), consideration should be given to the risk of additional systemic toxicity in patients receiving other local anaesthetics or agents structurally related to local anaesthetics, since the toxic effects are additive.
Ref. Core Data Sheet (CDS)
2. Use in pregnancy and nursing mothers
Lidocaine and prilocaine cross the placental barrier and may be absorbed by the fetal tissues. It is reasonable to assume that lidocaine and prilocaine have been used in a large number of pregnant women and women of child-bearing age. No specific disturbances to the reproductive process have so far been reported, e.g. an increased incidence of malformations or other directly or indirectly harmful effects on the fetus (refs. 38,39 in Core Data Sheet (CDS)).
Lidocaine and, in all probability, prilocaine are excreted in breast milk, but in such small quantities that there is generally no risk of the child being affected at therapeutic dose levels (ref 40 in CDS).
Ref. Patch and Cream Core Data Sheets (June 2002) Section:- 4.6 Pregnancy and lactation
3. Can EMLA be used to separate preputial adhesions?
In most boys referred for circumcision preputial adhesions are the only problem, but these can predispose to recurrent balanitis.
In this abstract MacKinlay describes a simple technique using EMLA cream on 39 boys aged 2 to 12 years referred for circumcision, none of whom had a retractable foreskin. This technique allowed the adhesions to be separated painlessly in the outpatient clinic.
The cream was applied under an occlusive dressing and left for 60 minutes before the adhesions were separated with a probe and a gauze swab. The procedure was completely pain free in 32 boys. One boy had to undergo a repeated procedure because he failed to follow the advice regularly to retract his foreskin in the three weeks after the procedure.
Only one boy had to undergo circumcision later because of fibrous phimosis. In many boys referred for circumcision separation of preputial adhesions is all that is needed, and the use of this local anaesthetic technique avoids the need for general anaesthesia.
Ref. MacKinlay GA. (1988)
Save the prepuce. Painless separation of preputial adhesions in the outpatient clinic.
BMJ 1988;297:590-91. (English)
(AEMLA-23165 AEMLA-0074)
4. What are the plasma concentrations of prilocaine and lignocaine after 24 hour application of leg ulcers?
Although EMLA has been extensively studied for the relief of acute treatmetn related pain from the sharp debridement of leg ulcers, no previous data exists on the systemic absorption following prolonged application in patients with chronic leg ulcers.
The study by Stymne and Lillieborg describes a single 24 hour application in 10 patients with painful leg ulcers. Venous blood samples were drawn between 0.5 and 27 hours and analysed by gas chromatography. Peak plasma levels were in the range of 185 - 705 ng/ml and 62 - 277 ng/ml for lignocaine and prilocaine respectively. Peak concentrations were reached at 2 - 4 hours and were well below toxic levels. The cream was well tolerated by all patients.
The analgesic efficacy of EMLA for the relief of chronic ulcer pain deserves further study but at the current time is not included in the licenced label in any country.
Ref. Stymne B and Lillieborg S
Plasma concentrations of lignocaine and prilocaine after 24 h application of analgesic cream (EMLA) to leg ulcers
British Journal of Dermatology 2001, 145, 530 – 534
5. The use of EMLA as an analgesic for anal fissures. Do you consider that this indication IS INCLUDED IN the indication genital mucosa?
In the documentation for what we call "EMLA genital mucous membranes" there were a number of patients who actually had treatment of condylomata on the anal mucosa. We therefore consider it included in the IDS for "Genitals" from a safety point of view. However, from an efficacy point of view it is more difficult:
For the cautery of condylomata one of our investigators, Dr Ljunghall, told AZ that it seemed very difficult to find an optimal application time: some patients had good anesthesia after 10-20 minutes, others had a lot of pain during treatment. The individual variation in tissue penetration can thus be expected to be very large.
There is one double-blind study conducted by the Swedish marketing company on EMLA for defecation pain after haemorrhoidectomy. EMLA/Placebo was applied for 10 minutes, however, in the 38 patients treated there was no difference in analgesic efficacy compared to placebo.
The question, however, appears to be proposing to use EMLA as an analgesic rather than as an anaesthetic, i.e. a long duration of action is required. In this situation EMLA is not very good on the mucous membranes ie. it has a quick absorption but short effect, less than 30 minutes. Xylocaine(R) ointment is recommended if prolonged analgesia for anal fissures is desired.
Ref. Personal Communication - Stefan Lillieborg, AstraZeneca
6. Can EMLA be used for the management of pain in burns patients?
AstraZeneca has performed one study of EMLA prior to debridement of burns. In an open pharmacokinetic study a dose of 5 g EMLA was applied for 30 minutes to burns measuring a maximum of 25 cm2. The results are summarised below. There is also a published study on the use of EMLA for postburn pruritus in children. (Abstract below). EMLA is not approved by any regulatory authority for application to burns. You should be aware that the commercially available EMLA cream is not sterile, although the bacterial quality of the cream is very good since both lidocaine and prilocaine have antibacterial and antiviral activity. Commercially available EMLA was used in the published pediatric study.
Summary of AstraZeneca study:
Eight male patients aged 22-59 scheduled for cleansing and debridement of 2nd degree burns participated. 5 g of Emla 5% cream sterile was applied to burns with a selected area of 25 cm2 and covered with plastic film for 30 minutes. Venous blood samples were taken prior to and up to 120 minutes after the application. The maximum plasma concentrations of lidocaine ranged from 47 to 412 ng/ml and those of prilocaine from 40 to 206 ng/ml. Six patients had t-max of lidocaine at 15 minutes and 2 patients had t-max at 30 minutes. Six patients had t-max of prilocaine at 30 minutes and 2 patients had t-max at 60 minutes. 120 minutes after the initial application, the plasma concentration of lidocaine was below 100 ng/ml and for prilocaine below 50 ng/ml for most of the patients. One patient reported a moderate burning sensation. There were no reports of redness or oedema.
As a comparison, the toxic threshold for initial CNS reactions of lidocaine or prilocaine is 5000-6000 ng/ml of either agent.
There is one published study of a lidocaine cream 5% available. Patients with partial-thickness burns greater than 5% of total body surface area (TBSA) were included in a study of the analgesic efficacy of 5% lidocaine cream for relief of burn pain (Brofeldt et al).
30 patients aged 14 to 63 years with burns involving 5% to 28% of TBSA participated. 1 mg of lidocaine (20 mg of cream) was applied per square centimetre burn and covered with gauze. Lidocaine plasma levels were measured up to 4 hours in 24 patients given 700 to 4500 mg lidocaine (14 to 90 g cream). Ten patients obtained a "reliably measurable" lidocaine level greater or equal to 1 ug/mL, which remained over the 4 hours of plasma sampling.
Application of up to 2000 mg of lidocaine (40 g cream) on an area up to 2000 cm2 resulted in plasma levels of 1 ug/mL or less. The maximal area treated, 28% TBSA, was treated with 4500 mg lidocaine (90 g cream), and gave a plasma level of 5.8 ug/mL. The peak concentrations achieved increased with increasing dose of lidocaine applied. No signs of systemic toxicity were reported. Because of the wide range in plasma levels observed with the 3000-mg application, the authors recommended caution in applying greater than 2000 mg lidocaine (40 g ointment) to the burn wound. They also suggested that lidocaine may have been retained within the gauze, providing a slow-release effect.
30 patients were evaluated for relief of their burn pain vs their baseline pain, measured 30 min after administration of systemic analgesics. Application of lidocaine cream 5% significantly reduced VAS pain scores compared to baseline, from a mean of 80-85 mm to 23-30 mm. Burns larger than 30% of TBSA was associated with a minimal decrease in pain score. This may be related to the fact that patients with large burns were usually more sedated, and possibly the total burn area could not be covered by the cream. In patients with facial burns, which were not covered by gauze, the patient usually requested reapplication of lidocaine after 4 -6 hours because of return of pain. Patients with burns on other parts of the body had gauze applied, and were observed to have a longer duration of analgesia.
Plasma levels after the use of topical lidocaine jelly in 6 patients with burns sized up to 1987 cm2 are reported by Read et al. All burn patients experienced rapid relief of their pain, which lasted up to the next dressing change:
Abstract
Topical local anaesthesia offers an important adjunct to several plastic surgery procedures, provided that it does not cause systemic toxicity or prevent the healing process. Absorption of a sterile topical lignocaine jelly was assessed in patients undergoing treatment of skin graft donor sites, flap donor sites and burns. There was a marked degree of absorption only in patients with thermal burns, in which case it depended on the surface area of the wound; although no toxic effects due to absorption were noted, caution in dosage is advisable. No complications of healing attributable to the preparation used were encountered.
Ref. Published Abstract: Leif Aanderud, Stefan Lillieborg. EMLA ANESTHETIC CREAM FOR DEBRIDEMENT OF BURNS: PLASMA CONCENTRATIONS OF LIDOCAINE AND PRILOCAINE. World Congress on Pain, San Diego 2002. Abstract 972-P242.
7. Why must EMLA cream be applied in a ”thick dab”?
When the EMLA cream is applied to the skin there is continuous absorption of active substances in the layer in contact with the skin. EMLA cream in a thick dab is a prerequisite for a constant supply of local anaesthetics into the cream layer close to the skin surface. Dose-response studies show that the minimum effective dose is 1 g per 10 cm2.
8. Why do we recommend 2 g cream before an injection if at the same time EMLA Patch containing 1 g emulsion is sufficient?
The minimum effective dose is 1 g per 10 cm2, which is in line with the content of EMLA patch. When applying cream under a Tegaderm occlusive dressing the cream is spread over an area of about 20 cm2. This is desirable e.g. if you need to cover more than one vein on the back of the hand, and you then need at least 2 g cream.
9. How often can EMLA be applied?
In children under 3 months old only one dose should be administered per day because of the risk of methaemoglobin formation in the event of a repeated dose. For older children and adults there is no precise limit as to how often EMLA can be applied. In clinical studies of haemodialysis, patients have been given EMLA on the same area of skin 2-3 times a week for 6 months, in most cases without significant skin reactions. In clinical studies of leg-ulcer patients 3-7 treatments a week have been administered, up to a maximum of 15 treatments in one month without apparent accumulation of lidocaine and prilocaine in the plasma. However, for daily use EMLA is not recommended for a longer time period than one week at a time.
10. Can EMLA cream also be used without a protective dressing for anaesthetising intact skin?
No, an occlusive dressing is needed to maintain EMLA cream’s high water content throughout the application period. EMLA cream’s special composition combined with high water content are properties that contribute to its ability to penetrate intact skin.
11. Why is it often recommended that EMLA be applied in two places?
Prior to a venipuncture or an injection, it is sometimes difficult to know exactly where the needle will be inserted. You should therefore apply EMLA Patch or cream on two skin areas so as to have a ”reserve site” to inject into.
12. If the Patch is too big for a child, can you divide it?
No, the plaster contains the amount required for adequate anaesthesia. If you divide the plaster leakage may occur and occlusion will be inadequate.
13. Are EMLA Patches to be seen as disposable articles, or can they be used twice?
They are disposable articles, as we do not know how much active substance remains after use.
14. Can EMLA plasters and cream be kept in a fridge?
Yes, but application to the skin straight from the fridge may feel somewhat unpleasant. EMLA must not, however, be frozen.
15. Can EMLA be used for anaesthesia before intramuscular or subcutaneous injections?
EMLA is a surface anaesthetic that can be expected to produce a good anaesthetic effect for the needle insertion pain, but probably not for all pain from the infiltration into deeper tissue such as muscles and subcutis. However, pain from intramuscular infiltration is significantly decreased compared with treatment with placebo cream. To achieve a completely painless intramuscular or subcutaneous injection, it is thus beneficial to combine EMLA with injection of a local anaesthetic. EMLA then provides painless injection of the local anaesthetic, which in turn anaesthetises the muscle or subcutis.
16. What is the best way to use EMLA before removal of mollusca contagiosa?
EMLA cream is applied in a thick dab over the skin areas to be treated. If the lesions are located some distance apart it may be appropriate to put a small-sized dab on each site to be treated, each dab covered by a piece of occlusive dressing. Leave the EMLA cream applied to the skin under the dressing for 1 hour (15-30 min if the patient is having atopic skin). The cream can then be removed and treatment commenced.
17. Can EMLA cream be used on skin areas affected by atopic dermatitis?
Yes, but with caution. The application time should be shortened to 15-30 minutes because of faster absorption on all parts of the skin in patients with atopic dermatitis, i.e. including skin areas without eczema.
18. Can EMLA be used for arterial puncture?
Arteries are located deeper than veins, and therefore arterial puncture requires a longer application time. If EMLA is applied for at least 90-120 minutes, published data indicates that the pain relief is comparable with or better than that achieved with subcutaneous Xylocaine injection. New data shows that the depth of skin anaesthesia further increases when EMLA has been applied for three hours (Wahlgren CF, Quiding H. J Am Acad Dermatol 2000; 42(4):584-8). This may further reduce the pain of an arterial injection.
19. Can EMLA be used before a prick-test?
Studies have shown that EMLA effectively removes the itching that can occur in conjunction with the prick test without influencing the result of the test, i.e. the size of the wheal. However, EMLA also decreases/prevents any erythema (“flare”), which thus cannot be used as an indicator of the test result Refs. Pipkorn U, Andersson M. Topical dermal anaesthesia inhibits the flare but not the weal response to allergen and histamine in the skin-prick test. Clin Allergy 1987;17:307-11, Wagner G, Barghorn A. Validity of skin prick testing for inhalational allergens after topical anaesthesia using a lidocaine-prilocaine-cream. Aktuel Dermatol 1999;25:382-5.
20. Can EMLA be used before vaccinations?
EMLA can be used as a dermal anaesthetic for vaccination pain, and provides significant pain relief compared with placebo, even with intramuscular vaccination. EMLA can be used in combination with most vaccinations. When injecting live vaccines intracutaneously (e.g. BCG) the vaccination response should be monitored because lidocaine and prilocaine have antibacterial and antiviral effects.
References:
1. Dohlwitz A, Hellenberg L, Svedmyr J, Tober L, Wigertz A. No negative influence of EMLA application prior to BCG vaccination. Acta Paediatr 1998; 87(4):480-1.
2. Halperin BA, Halperin SA, McGrath P, Houston T, Smith B. Eutectic mixture of local anaesthetic (EMLA(R)) reduces pain associted with diphtheria-tetanus-acelleluar pertussis-inactivated poliovirus-haemophilus influenzea B (DTaP-IPV-HIB) and Hepatitis B (HB) immunizations but does not affect the antibody response. In: ISPP2000 : The 5th International Symposium on Paediatric Pain, 18-21 June 2000, London, United Kingdom : Book of Abstracts. 2000; P7 (abstr).
3. Halperin SA, McGrath P, Smith B, Houston T. Lidocaine-prilocaine patch decreases the pain associated with the subcutaneous administration of measles-mumps-rubella vaccine but does not adversely affect the antibody response. J Pediatr 2000; 136(6):789-94.
4. Taddio A, Nulman I, Goldbach M, Ipp M, Koren G. Use of lidocaine-prilocaine cream for vaccination pain in infants. J Pediatr 1994; 124(4):643-8.
5. Taddio A, Nulman I, Reid E, Shaw J, Koren G. Effect of lidocaine-prilocaine cream (EMLA(R)) on pain of intramuscular Fluzone(R) injection. Can J Hosp Pharm 1992; 45:227-30.
6. Uhari M. A eutectic mixture of lidocaine and prilocaine for alleviating vaccination pain in
infants. Pediatrics 1993; 92(5):719-21.
7. Walsh Z, Bertilson SO. :Topical anaesthetic cream provides pain relief in tetanus vaccination:: Ytanestesikräm gav smärtlindring vid stelkrampsvaccination. Lakartidningen 1987; 84:611-12.
21. Can EMLA be used for capillary sampling, e.g. from the fingertip?
EMLA does not provide anaesthesia of the fingertip. It is not quite clear why this is, but it is believed that factors such as fast blood flow preventing the build-up of sufficient local anaesthetic tissue concentrations and the depth of the injection are involved.
22. Can EMLA be used for 24-hour treatment of painful leg ulcers?
EMLA is not recommended for continuous treatment of painful conditions. Constant application of
EMLA cream throughout the day with the aim of maintaining continuous anaesthesia of a painful leg ulcer might entail a degree of risk of the patient developing long-term hypersensitivity to local anaesthetics. It cannot be excluded that patients with large and/or several leg ulcers may develop excessively high plasma concentrations from local anaesthetics during application of EMLA cream for 24 hours. One study shows that a single dose of up to 10 g EMLA on leg ulcers up to a maximum size of 100 cm2 for 24 hours results in plasma levels five times lower than those were signs of toxicity may appear (Stymne B, Lillieborg S. Plasma concentrations of lignocaine and prilocaine after 24-hour application of analgesic cream (EMLA®) to leg ulcers. Br J Dermatology 2001;145:530-4).
23. Why should EMLA not be used on open wounds and sores?
Because of incomplete documentation of the absorption of EMLA on open sores, EMLA should not be used on broken skin (except on leg ulcers). With leg ulcers, systemic absorption is slower than with acute sores. Xylocaine® ointment is more suitable for use on open sores such as riding sores, removal of stings and for the cleaning of abrasions.
24. Can EMLA be used on mucosa?
EMLA can be used to anaesthetise the genital mucosa in adults. The absorption is very fast and anaesthetic onset time is achieved after only five minutes. EMLA should be applied for 5-10 minutes and the surgical/diagnostic procedure be performed immediately after cream removal (with longer application times than 15 minutes the analgesic efficacy decreases even while the cream is still applied, mainly because of high local blood flow). The anaesthetic duration is relatively shorter than on intact skin, with a mean of 15 – 20 minutes. EMLA should not be used on genital mucosa in children because of incomplete data on absorption.
References.
1. Ljunghall K, Lillieborg S. Local anaesthesia with a lidocaine/prilocaine cream (EMLA) for cautery of condylomata acuminata on the vulval mucosa. The effect of timing of application of the cream. Acta Derm Venereol 1989; 69:362-5.
2. Mansell-Gregory M, Romanowski B. Randomised double blind trial of EMLA for the control of pain related to cryotherapy in the treatment of genital HPV lesions. Sex Transm Infect 1998; 74(4):274-5.
3. Rylander E, Sjöberg I, Lillieborg S, Stockman O. Local anesthesia of the genital mucosa with a lidocaine/prilocaine cream (EMLA) for laser treatment of condylomata acuminata: A placebo-controlled study. Obstet Gynecol 1990; 75:302-6.
4. Van Der Burght M, Schonemann NK, Laursen JK, Arendt-Nielsen L, Bjerring P. Duration of analgesia following application of eutectic mixture of local anaesthetics (EMLA) on genital mucosa. Acta Derm Venereol 1993; 73(6):456-8.
5. Zilbert A. Topical anesthesia for minor gynecological procedures: a review. Obstetrical & Gynecological Survey 2002;57(3):171-8.
25. Does EMLA have a positive effect on the genital herpes virus infections?
EMLA has been studied for the relief of pain and symptoms of genital herpes infections with some effect in one study (Cassuto J. Topical local anesthetics and herpes simplex (letter). Lancet 1989; (8629):100-1) but a symptomatic or therapeutic effect of EMLA has not been reproduced in further studies.
26. Can EMLA be used before plucking eyebrows?
EMLA should be used with caution around the eyes, as it may cause irritation of the cornea. It may be used for pluckin eyebrows, though application of EMLA will make eyebrows harder to pluck, since their structure will become elastic and rubber-like.
27. Can EMLA be used before ear-piercing?
EMLA has been shown effective prior to injection of local anaesthetics into the ears (1). Some effect may be anticated also for ear-piercing. But there must still be a dab of cream, and it is important to cover the area properly so the cream does not dry out. EMLA should not be applied to an impaired tympanic membrane.
Ref. 1. Slator R, Goodacre TEE. EMLA cream on the ears - is it effective?: a prospective, randomised controlled trial of the efficacy of topical anaesthetic cream in reducing the pain of local anaesthetic infiltration for prominent ear correction. Br J Plast Surg 1995;48:150-3.
28. Can EMLA be used before hair removal?
EMLA significantly relieves the pain of laser hair removal as compared to placebo cream after a 60 min application.
References :
1. Hjorth N, Harring M, Hahn A. Epilation of upper lip hirsutism with a eutectic mixture of lidocaine and prilocaine used as a topical anesthetic. J Am Acad Dermatol 1991; 25:809-11.
2. Wagner RF Jr, Flores CA, Argo LF. A double-blind placebo controlled study of a 5% lidocaine/prilocaine cream (EMLA) for topical anesthesia during thermolysis. J Dermatol Surg Oncol 1994; 20(2):148-50.
29. Can EMLA be used before tattooing?
EMLA can be used as a cutaneous anasthetic prior to tattooing and also for tattoo removal.
References :
Juhlin L, Evers H, Broberg F. A lidocaine-prilocaine cream for superficial skin surgery and painful lesions. Acta Derm Venereol 1980; 60:544-6.
Tan OT. Stafford TJ. EMLA for laser treatment of portwine stains in children. Lasers in Surgery & Medicine. 12(5):543-8, 1992.
30. Can EMLA be used in animals?
EMLA is not approved for use in animals.
31. When should you use cream, and when Patch?
From a medical standpoint it does not matter whether you use plasters or cream, however plasters are easier and more convenient to apply. Plasters may be too big for children under 3 years. For puncture of e.g. scalp veins, plasters are also suitable in young children (removal of some hair may be necessary).
32. From what age can EMLA be used?
EMLA can be used on adults and children, including full term neonates (gestational age at least 37 weeks).
33. For how long should EMLA be applied to the skin?
The application time for EMLA on intact skin is at least 1 hour for satisfactory and reliable anaesthesia before an injection. The anaesthetic effect increases with a longer application time, which is above all of significance for major superficial surgical procedures, e.g. harvesting of split-skin grafts. Also for some minor procedures of some depth a longer application time will be beneficial, e.g. for skin biopsies. With these applications the application time should be extended to at least 2 hours. For anaesthesia of male genital skin 15-30 minutes is adequate, because of the thin stratum corneum in this location. For anaesthesia of genital mucosa in women EMLA should be applied for 5-10 minutes (with longer times the analgesic efficacy decreases, mainly because of high local blood flow).
34. How will the anaesthesia be effected if you apply EMLA to intact skin for a period of less than 1 hour?
An application time of less than 1 hour creates an unreliable anaesthetic effect, whereby individual variations can be significant. This means you can never predict which patients will experience satisfactory anaesthesia after 40 minutes and in which patients the skin will not be numb. However, in patients with atopic dermatitis 15-30 min is sufficient for a minor procedure. Also, for the curettage of molluscum contagiosum, about 80-90% of patients will experience no or only mild pain after an EMLA application of about 30 minutes.
References :
1. de Waard van der Spek FB, Oranje AP, Lillieborg S, Hop WCJ, Stolz E. Treatment of molluscum contagiosum using a lidocaine/ prilocaine cream (EMLA) for analgesia. J Am Acad Dermatol 1990; 23:685-88.
2. Rönnerfält L, Fransson J, Wahlgren CF. EMLA cream provides rapid pain relief for the curettage of molluscum contagiosum in children with atopic dermatitis without causing serious application-site reactions. Pediatr Dermatol 1989; 15(4):309-12.
35. How long is the duration of skin anaesthesia after EMLA has been removed?
If EMLA remains in place for 1-2 hours the anaesthetic effect will be satisfactory for at least two hours after the removal of the cream. If the cream remains in place for at least 1 hour the analgesic effect will begin to diminish 5 hours after the time of application.
36. What is the depth of skin anaesthesia?
For a 60-minute EMLA application the depth of anaesthesia is approx. 2 mm, and for 120 minutes approx. 3 mm (Wahlgren CF, Quiding H. J Am Acad Dermatol 2000; 42:584-8). The depth of anaesthesia can vary slightly depending on the area of the body, influenced by both skin thickness and local blood flow.
References :
1. Arendt-Nielsen L, Bjerring P, Nielsen J. Regional variations in analgesic efficacy of EMLA (R) Cream Quantitatively evaluated by argon laser stimulation. Acta Derm Venereol 1990; 70:314-18.
2. Larsson BA, Norman M, Bjerring P, Egekvist H, Lagercrantz H, Olsson GL. Regional variations in skin perfusion and skin thickness may contribute to varying efficacy of topical, local anaesthetics in neonates. Paediatr Anaesth 1996; 6(2):107-10.
37. The skin may become pale or red where an EMLA Patch or EMLA cream has been applied. Why is this?
With a short application time (60-90 min.) the area of skin where EMLA has been applied may look pale, whilst the skin may instead redden as a result of a longer application time. The effect is the result of hydration (water uptake) of the skin, and of the fact that local anaesthetics directly affect the capillaries (Juhlin L, Evers H. EMLA: A new topical anesthetic. Adv Dermatol 1990; 5:75-92). It is mainly the superficial vascular bed that is effected. The veins where you make a venipuncture are not very much effected (Egekvist H. Bjerring P. Acta Dermato-Venereologica 2000;80:340-3.). Both these skin colour changes are normal reactions to local anaesthetics and disappear after a few hours.
38. What can you do to avoid paleness concealing the vessel?
You may leave the dressing on a little longer since paleness is usually seen after the shortest application times. Some paediatric departments wait 5-15 minutes after having removed EMLA and the veins then stand out better – also, 15 minutes after the occlusive dressing is removed the skin dries and paleness from the hydration disappears (Egekvist H. Bjerring P. Effect of EMLA cream on skin thickness and subcutaneous venous diameter. A randomized, placebo-controlled study in children. Acta Dermato-Venereologica 2000;80:340-3.).
39. How is the effect of EMLA influenced by skin pigmentation?
EMLA is equally effective and has the same anaesthetic onset time in of both light and pigmented skin (Riendeau LA et al. Evaluation of the analgesic efficacy of EMLA cream in volunteers with differing skin pigmentation undergoing venipuncture. Reg Anesth Pain Med 1999; 24(2):165-9).
40. Does EMLA effect the results of clinical chemistry and haematology tests?
EMLA does not significantly affect the results of clinical chemistry and haematology tests.
References :
Amdisen A. Glud V. No influence from topical application of EMLA cream before blood sampling on routine clinical chemistry and haematology measurements. European Journal of Clinical Pharmacology. 1991;41(6):619-20
41. How does purpura occur?
Purpura can manifest itself as petechiae, i.e. millimetre-sized maculae = small point shaped (millimetre sized) skin haemorrhages, or as echymoses = blood effusions, major infiltrating haemorrhages in tissues, large bruises. Petechiae (purpura) may occur in patients with some form of skin damage, e.g. atopic dermatitis, that makes absorption faster and uptake greater. The reaction begins with reddening, which then gives way to petechiae. In many such cases EMLA cream will have remained on the skin for longer than usual. Patients with atopic dermatitis do not need a particularly long application time to experience adequate anaesthesia.
42. How common are allergic reactions to EMLA?
Allergic reactions to local anaesthetics of the amide type, such as lidocaine and prilocaine, are very rare; the frequency is probably less than one case per million doses. It has also transpired that most such reactions that have been reported have not been caused by allergy to the actual local anaesthetic but by allergy to the preservatives previously used in injection solutions. Most of the allergic reactions occurring are benign skin reactions. In patients who have displayed such reactions (primarily urticaria), at least theoretically there is a risk of renewed use of the agent causing a serious anaphylactic reaction. That is why the prescribing information includes information about anaphylactic reactions. However, such reactions are far rarer with local anaesthetics than with a number of common drugs, e.g. penicillin V and acetylsalicylic acid.
43. What happens if children ingest the cream?
EMLA tastes unpleasant, which means the risk is probably low. If a child nevertheless swallows a large amount of EMLA cream, most of it is metabolised in the liver during the first passage. The metabolites that form are to a certain extent pharmacologically active, which means toxic reactions may occur if the dose is large. EMLA has hitherto (up until 2003) been used for treating over 100 million patients, and no side effects as a result of having ingested EMLA have been reported. Side effects of local anaesthetics are very rare at normal doses.
44. What is carboxypolymethylene?
Carboxypolymethylene is a thickening agent.
45. What is the patch made of?
EMLA plaster: the sticking plaster is an acrylate adhesive. The plaster does not contain latex.
46. Is there any latex in the protective dressing?
No, the protective dressing does not contain any latex.
47. Is latex present anywhere in the pack?
Latex is only present at the end of the tube, where it is sealed, but it never comes into contact with the cream. There is no latex in the tube cap or in any other part of the packaging material.
48. How can I estimate the dose from the 30 g EMLA cream tube?
1 g of EMLA cream administered from the 30 g aluminium tube corresponds to a length of cream string of approximately 3.5 cm.
49. Is the effect of EMLA different in elderly patients?
In clinical studies of EMLA on intact skin, no differences in anaesthetic onset time, analgesic efficacy or adverse events were observed between geriatric patients (aged 65-96 years) and younger patients (Wahlgren CF, Lillieborg S. Split-skin grafting with lidocaine-prilocaine cream: A meta-analysis of efficacy and safety in geriatric versus nongeriatric patients. Plastic and Reconstructive Surgery 2001;107(3):750-6.).
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