The active ingredient in Retin-A and Retin-A Micro is tretinoin, which comes in several strengths. Tretinoin treats acne by promoting peeling of treated areas and unclogging pores, according to the National Library of Medicine. The medication is topical, meaning it is applied to your skin through a gel, cream or liquid. It is a prescription medication and should be used with care, under medical supervision, as it can cause skin irritation. It may temporarily increase acne as it is working. Several weeks are required to see results. This medication should not be used if you are pregnant or nursing.
Retin-A Gel comes in two strengths, 0.025 percent tretinoin or 0.01 percent tretinoin. Retin-A in all forms should be applied sparingly, both to reduce skin irritation and because more medicine does not work any better or faster. If you apply too much gel, it will "pill," which minimizes the likelihood of over-application. Squeeze out a half-inch strip or less onto your fingertip. Dab it over cheeks, forehead and chin, and smooth it in. The gel should become invisible. If it doesn't, or if dry flaking occurs within a minute, you are using too much.
Retin-A Cream has three strengths of tretinoin: 0.1 percent, 0.05 percent, and 0.025 percent. Like the gel, the cream should become invisible almost immediately after you smooth it into your skin, or you are using too much. Dab and spread, as you do for gel--a half-inch or less of cream squeezed onto your fingertip should be enough. As you use Retin-A, you will get a feel for how much or how little you need to use for your particular skin type.
Retin-A Liquid contains 0.05 percent tretinoin. Apply it to the skin where the acne lesions appear by using your fingertip, a gauze pad or a cotton swab. Be careful not to over-saturate the gauze or cotton so that you don't get tretinoin in the corners of your mouth, eyes or nose. Any tretinoin should be applied carefully only to affected areas, avoiding delicate areas that may be more susceptible to irritation.
Retin-A Micro is also a gel, but delivered through different ingredients than Retin-A Gel. Retin-A Micro comes in strengths of 0.1 percent and 0.04 percent. Studied in a half-face comparison trial in subjects without acne, Retin-A Micro 0.1 percent was less irritating to the skin than tretinoin cream 0.1 percent. The lower irritancy may be due to the inactive ingredients, which deliver the medication, according to manufacturer information. Retin-A Micro may be dispensed from a tube or a pump. Squeeze or pump the medication in the size of a pea to be dabbed onto the skin and smoothed in.
Though tretinoin is an ideal treatment for mild acne, according to San Francisco State University (SFSU), it is irritating to many skin types. The SFSU Student Health Services skin clinic recommends minimizing burning, peeling and redness by beginning with the lowest strength cream, at 0.25 percent tretinoin. Apply the medication on a 3-2-1 schedule--every third night in week one, every other night in week two, and every night in week three--to give your skin time to tolerate the effects.