Topical retinoids are derivatives of vitamin A that are applied to the skin to treat mild to moderate acne. There are a number of different retinoids, and trade names may differ from country to country and by manufacturer. They are available in various topical forms, including creams and gels. Combination products containing a retinoid and an antibiotic are also available in some countries. A prescription from a doctor is usually required.
There are a number of different topical retinoids, including isotretinoin, acitretin, tretinoin and adapalene. Their exact mechanism of action is still not completely understood, but it is thought that they act by reducing adhesion between the skin cells, which aids desquamation, or skin shedding, and inhibits comedone, or blackhead, formation. This is effective for treating acne where comedones, papules and pustules predominate. Topical retinoids are not expected to be particularly effective for severe acne or deep nodular cystic acne.
As with any medication, topical retinoids may have adverse effects. The most common of these are drying of the skin and photosensitivity. It is recommended that they are applied at night and the skin washed in the morning, before sun exposure, to minimize this effect. A good sunscreen should be used while on treatment.
Irritation of the skin may also occur. If irritation is severe, discontinuation of treatment may be recommended. Topical retinoids should not be applied to open skin, abrasions, mouth, eyes or mucous membranes.
While systemic absorption of topical retinoids when used on a small area is expected to be minimal, they may interact with concomitant medications. These should be discussed with the prescribing doctor. Caution should be exercised when using abrasive cleaners, and the use of peeling agents such as benzoyl peroxide is not recommended while using topical retinoids.
Vitamin A may have harmful effects on the fetus, so pregnancy or desired pregnancy should be excluded before topical retinoids are started. Reliable contraception should be provided where necessary in women of childbearing age. The use of topical retinoids is not recommended during lactation. Any other disease conditions should also be discussed with the prescribing doctor.
Topical retinoids are usually applied once or twice daily. The recommended dosage should never be exceeded, as this will increase the chances of adverse effects. It may take six to eight weeks of treatment for the full therapeutic effect to be seen. Should adverse effects be experienced, or a lack of therapeutic effect, medical advice should be sought.