FDA Fetal Risk Categories
Treatment for Common Dermatoses in Pregnancy

Category A
Controlled studies in women fail to demonstrate a risk to the fetus in the first trimester, there is no evidence of a risk in later trimesters, and the possibility of fetal harm appears remote.
Category B
Either animal reproduction studies have not demonstrated a fetal risk but there are no controlled studies in pregnant women, or animal reproduction studies have shown on adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the first trimester (and there is no evidence of risk in later trimesters).
Category C
Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal or other) and there are no controlled studies in women, or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the fetus.
Category D
There is positive evidence of human fetal risk, but the benefits from use in pregnant women may be acceptable despite the risk (eg, if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective).
Category X
Studies in animals or human beings have demonstrated fetal abnormalities or there is evidence of fetal risk based on human experience or both, and the risk of use of the drug in pregnant women clearly outweighs any possible benefit. The drug is contraindicated in women who are or may become pregnant.

Treatment for Common Dermatoses in Pregnancy

Tinea Versicolor
Category B: Ciclopirox (Loprox); clotrimazole 1% (Lotrimin)
Category C: Miconazole (Monistat) - the absence of congenital malformations when used for vulvovaginal candidiasis suggests that limited topical use is an alternative for tinea versicolor. Likewise, econazole 1% cream (Spectazole) and ketoconazole 2% cream (Nizoral). Limit use to once daily and not more than 2 weeks. Also, limited use of category C shampoo products, selenium sulfide (Selsun) and ketoconazole (Nizoral) appear safe. Because of fetal limb anomalies, oral azoles should be used only when no alternatives are available or topical agents have failed.

Category C: Topical corticosteroids continue to be the mainstay for scalp and localized plaque psoriasis. Use the least potent preparation (Table). Maternal adrenal suppression can occur from 2 gm daily use of a class 1 or 5 g of a class 2 corticosteroid. There is evidence that corticosteroid affect the fetal endocrine system. Another category C drug, without studies in pregnant women, calcipotriene 0.005% ointment, cream or solution (Devonex) is an excellent nonsteroidal antipsoriatic agent not associated with cutaneous atrophy. Anthralin (Anthra-derm, Drithocreme) ointment or cream is another topical option; side effects of skin irritation and staining make it less desirable. Cyclosporine (Neoral), a potent oral immunosuppressive agent, has been found to be effective in widespread psoriasis. It is not an animal teratogen, and is unlikely to be a human teratogen; yet, because of the availability of alternative medications, use in pregnant women should be limited. UV light may result in fetal neural tube defects, especially in the first weeks of gestation. Exposure in the later stages of pregnancy may be possible. Psoralen-UV-A (PUVA), effective for symptomatic control of severe psoriasis and posing less risk than alternative therapies, is considered a potential teratogen and warrants avoidance during pregnancy.
Categories D and X: Methotrexate, a folic acid antagonist, may cause neural defects when used in the first trimester. Tazarotene 0.05% or 0.1% gel, a retinoid is a category X drug.

Category B: H1 blockers - diphenhydramine (Benadryl) and the newer nonsedating cetrizine (Zyrtec) and loratidine (Claritin). H2 antagonists: cimetidine (Tagamet). Doxepin hydrochloride 5% cream (Zonalon), a potent H1 and H2 blocker, applied 4x daily should not be used more than 8 days.
Category C: Hydroxyzine (Atarax) and fexofenadine (Allegra). Systemic corticosteroids are useful for severe urticaria; use the least potent effective agent.

Source: Common Dermatoses: How to Treat Safely and Effectively During Pregnancy, Part 2. Dawn Fisher, MD and David Kaplan, MD - CONSULTANT, July 2001.