Lidocaine and prilocaine cream is a topical numbing cream used to reduce or eliminate pain on the skin before medical procedures. Sold under the brand name EMLA, the standard formulation contains 2.5% lidocaine and 2.5% prilocaine in a 1:1 ratio. It’s applied to intact skin or mucous membranes to provide local anesthesia, making needle sticks, minor surgeries, and other procedures far more comfortable for both adults and children.
Common Medical Uses
The cream is most frequently used before procedures that involve breaking the skin. IV catheter placement and blood draws are the classic examples, especially in pediatric settings where needle anxiety is high. It’s also used before skin graft harvesting, laser treatments, mole or wart removal, and cosmetic procedures like dermal fillers or microneedling. In dermatology offices, it’s a staple for numbing skin before biopsies or minor excisions.
On genital mucous membranes, the cream serves a different set of purposes. It can numb the area before injections of deeper local anesthetic, before procedures like genital wart removal, or before minor gynecological procedures. The absorption profile is notably different on mucosal tissue compared to regular skin, which changes both how it’s applied and how quickly it works.
Off-Label Use for Premature Ejaculation
One of the most searched uses of lidocaine and prilocaine cream is for premature ejaculation. While not its FDA-approved purpose, the cream has been studied for this application. In a study published in The Journal of Urology, men applied 2.5 grams of the cream to the penis 30 minutes before sexual contact, then covered it with a condom. Of 11 patients, five rated the result as excellent, reporting that ejaculation occurred 15 to 20 minutes after penetration. Four more rated it as “better,” with ejaculation at 5 to 10 minutes. Two reported no change. The desensitizing effect is essentially the same mechanism that numbs skin before a needle, just applied to reduce sensation enough to delay climax.
How It Works
Both lidocaine and prilocaine are local anesthetics that block pain signals by plugging the sodium channels on nerve cells. Normally, when you feel pain, sodium rushes into nerve cells through tiny channels, generating an electrical signal that travels to the brain. These two drugs physically enter and block those channels from the inside, preventing the signal from firing. The combination of two anesthetics in a 1:1 ratio creates what chemists call a eutectic mixture, meaning the two drugs together melt at a lower temperature than either one alone. This keeps the cream in an oil-based form that penetrates skin more effectively than either ingredient could on its own.
How to Apply It
The timing and technique vary depending on where you’re applying it and what procedure you’re preparing for.
On intact skin, a thick layer goes on and then gets covered with an airtight (occlusive) dressing, often a clear adhesive film like Tegaderm or even plastic wrap. This covering is essential because it traps the cream against the skin and forces absorption. For a simple blood draw or IV start, you need at least 60 minutes under the dressing. For deeper procedures like skin graft harvesting, that extends to at least two hours. The numbing effect reaches its peak at two to three hours after application and lasts one to two hours after you wipe the cream off.
On genital mucous membranes, the timeline is dramatically shorter. Full numbing can happen in as little as 5 to 15 minutes, and a covering isn’t required for the cream to absorb. A bandage or dressing can still help simply to keep the cream from wiping off, but the mucosal tissue absorbs the medication readily on its own.
Side Effects at the Application Site
The most common reactions are localized and temporary. You can expect some combination of paleness (blanching), redness, or mild swelling right where the cream was applied. These are normal vascular responses to the anesthetic and typically resolve within an hour or two after removal. Some people notice a brief burning or itching sensation when the cream first goes on, before the numbing takes effect. Genuine allergic reactions to either lidocaine or prilocaine are rare but possible.
Methemoglobinemia Risk
The most serious potential side effect is a blood condition called methemoglobinemia, where a breakdown product of prilocaine changes hemoglobin so it can no longer carry oxygen effectively. At low levels this causes no symptoms. When affected hemoglobin rises above 10%, it can cause a bluish tint to the skin, shortness of breath, and fatigue. Levels above 60% can be life-threatening.
In healthy adults, this risk is very low at normal doses. It becomes a real concern in a few specific situations:
- Infants and young children: Their smaller body weight means a given amount of cream represents a proportionally larger dose, and their enzyme systems for clearing the problematic metabolite are less mature.
- People with G6PD deficiency: This inherited enzyme shortage, which affects roughly 400 million people worldwide, impairs the body’s ability to correct the hemoglobin change.
- People taking certain other medications: Nitrate-containing drugs, sulfonamide antibiotics, antimalarials, and even acetaminophen in large amounts can compound the risk because they also promote the same hemoglobin change.
- People with anemia or heart/lung disease: These conditions reduce the body’s oxygen reserves, making even a modest drop in oxygen-carrying capacity more dangerous.
In adults, prilocaine doses above 400 mg have been linked to methemoglobinemia. A full 5-gram tube of standard cream contains 125 mg of prilocaine, so exceeding that threshold requires applying quite a lot. The risk is more practical in children, where smaller surface areas and lower body weights narrow the margin of safety considerably.
Where Not to Apply It
The cream is designed for intact skin and specific mucous membranes only. It should not go on open wounds, cuts, or broken skin, because the anesthetics would absorb too rapidly into the bloodstream. It’s also not meant for use near the eyes or on the ear canal. Applying it over large body surface areas increases the total amount of drug absorbed and raises the risk of systemic effects, so covering broad areas requires careful attention to dose limits based on body weight, especially in children.