Why is Retin-A prescribed?
Retin-A, Avita, and Renova contain the skin medication tretinoin. Retin-A and Avita are used in the treatment of acne. Renova is prescribed to reduce fine wrinkles, discoloration, and roughness on facial skin (as part of a comprehensive program of skin care and sun avoidance).
Retin-A is available in liquid, cream, or gel form, and in a stronger gel called Retin-A Micro. Avita comes only as a gel. Renova is available in cream form only.
Most important fact about Retin-A

While using Retin-A, Avita, or Renova, keep exposure to sunlight, including sunlamps, to a minimum. If you have a sunburn, do not use the medication until you have fully recovered. Use of sunscreen products (at least SPF 15) and protective clothing over treated areas is recommended when exposure to the sun cannot be avoided. Weather extremes, such as wind and cold, may be irritating and should also be avoided while using these products.
How should you use Retin-A ?
Retin-A and Avita should be applied once a day, in the evening, to the skin where acne appears, using enough to lightly cover the affected area. The liquid form may be applied using a fingertip, gauze pad, or cotton swab. If you use gauze or cotton, avoid oversaturation, which might cause the liquid to run into areas where treatment is not intended.
Renova is also applied once daily in the evening. Use only enough to lightly cover the affected area. Before you use Renova, wash your face with a mild soap, pat your skin dry, and wait 20 to 30 minutes. Then apply a dab of Renova cream the size of a pea and spread it lightly over your face, avoiding your eyes, ears, nostrils, mouth, and open wounds.
You may use cosmetics while being treated with these products; however, you should thoroughly cleanse the areas to be treated before applying the medication.
If your skin becomes too dry, you may want to use petroleum jelly or another emollient during the day.
If there is no immediate improvement, or new blemishes appear, don't get discouraged; it takes weeks for the medicine to take effect. Continue applying the prescribed amount. (Do not increase the dosage; it may irritate your skin.)
Do not stop treatment when improvement finally occurs. You must continue therapy to maintain the beneficial effect.
--If you miss a dose...
Resume your regular schedule the next day.
--Storage instructions...
Store at ordinary room temperature. Do not freeze Renova.
What side effects may occur?
If you have sensitive skin, the use of Avita or Retin-A may cause your skin to become excessively red, puffy, blistered, or crusted. If this happens, notify your doctor, who may recommend that you discontinue the medication until your skin returns to normal, or adjust the medication to a level that you can tolerate.
An unusual darkening of the skin or lack of color of the skin may occur temporarily with repeated application of Avita or Retin-A.
Side effects of these medications are generally not severe and may include burning, dry skin, itching, peeling, redness, and stinging.
Why should Retin-A not be prescribed?
If you are sensitive to or have ever had an allergic reaction to either of these products, avoid using them.
The safety and effectiveness of long-term use of Retin-A in the treatment of disorders other than acne have not been established.
The safety and effectiveness of Renova 0.05 percent cream have not been established in children under age 18, adults over age 50, and people with heavily pigmented or sun-damaged skin, nor in periods of greater than 48 weeks of daily use.
The safety and effectiveness of Renova 0.02 percent cream have not been established in children under age 18, adults over age 71, and people with sun-damaged skin, nor in periods of greater than 52 weeks of daily use.
Special warnings about Retin-A
Be sure to keep these products away from the eyes, mouth, angles of the nose, and mucous membranes.
The medication may cause a brief feeling of warmth or slight stinging when applied. If it causes an abnormal irritation, redness, blistering, or peeling of the skin, notify your doctor. He may suggest that you use the medication less frequently, discontinue use temporarily, or discontinue use altogether. If a severe sensitivity reaction or chemical irritation occurs, you will probably need to stop using the drug.
If you have eczema (skin inflammation consisting of itching and small blisters that ooze and crust over) or other chronic skin conditions, use these products with extreme caution, as they may cause severe irritation.
During the early weeks of acne therapy, a worsening of the condition may occur due to the action of Avita or Retin-A on deep, previously unseen areas of inflammation. This is not a reason to discontinue therapy, but do notify your doctor if it occurs.
Retin-A gel and Avita are flammable and should be kept away from heat and flame.
Renova will not eliminate wrinkles, repair damage done by the sun, or reverse the aging process. After you stop using Renova, it is best to continue using a sunscreen and avoiding the sun.
Possible food and drug interactions when taking Retin-A
If these medications are used with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining Avita or Retin-A with the following:

Preparations containing benzoyl peroxide, such as Benzac AC Wash 5, Benzshave, Desquam-E, PanOxyl
Preparations containing sulfur (ointments and other preparations used to treat skin disorders and infections)
Resorcinol (a drug, used in ointments to treat acne, that causes skin to peel)
Salicylic acid (a drug that kills bacteria and fungi and causes skin to peel)
"Resting" your skin is recommended between use of the above preparations and treatment with Avita or Retin-A.
Do not use Renova if you are taking other drugs that increase sensitivity to sunlight. These include:

Certain antibiotics, including Cipro, Noroxin, and tetracycline
Major tranquilizers such as Thorazine and Mellaril
Sulfa drugs such as Bactrim and Septra
Thiazide drugs (water pills) such as Diuril and HydroDIURIL
Caution should be exercised when using Avita, Retin-A, or Renova in combination with other topical medications, medicated or abrasive soaps and cleansers, soaps and cosmetics that have a strong drying effect, products with high concentrations of alcohol, astringents, spices, or lime (especially the peel), permanent wave solutions, electrolysis, hair depilatories or waxes, or other preparations that may dry or irritate the skin.
Special information if you are pregnant or breastfeeding
The effects of Retin-A during pregnancy have not been adequately studied. If you are pregnant or plan to become pregnant, inform your doctor immediately.
Do not use Renova or Avita during pregnancy or if there is a good chance that you will become pregnant.
It is not known whether the drug appears in breast milk. Use with caution when breastfeeding.
Recommended dosage
RETIN-A AND AVITA
Apply once a day in the evening.
You should begin to notice results after 2 to 3 weeks of treatment. More than 6 or 7 weeks of treatment are needed before consistent beneficial effects appear.
Once acne has responded satisfactorily, it may be possible to maintain the improvement with less frequent applications or other dosage forms. However, any change in formulation, drug concentration, or dose frequency should be closely monitored by your doctor to determine your tolerance and response.
RENOVA
Apply just enough to lightly cover the affected area once daily at bedtime. Do not apply more than the recommended amount; it will not improve results and may cause increased discomfort. You will see the most improvement during the first 24 weeks of therapy. After that, Renova will simply maintain the improvement. When therapy is stopped, the improvement will gradually diminish.
Overdosage
Applying Avita, Retin-A, or Renova excessively will not produce faster or better results, and marked redness, peeling, or discomfort could occur.