Cyproheptadine Safety in Pregnancy
Cyproheptadine can be used during pregnancy when clearly needed, as it is FDA Pregnancy Category B with no evidence of harm to the fetus in animal studies and limited human data showing no increased risk of abnormalities. 1
FDA Classification and Animal Studies
Cyproheptadine is classified as FDA Pregnancy Category B, meaning reproduction studies in rabbits, mice, and rats at doses up to 32 times the maximum recommended human dose have revealed no evidence of impaired fertility or harm to the fetus. 1
However, the drug was fetotoxic in rats when given by intraperitoneal injection at doses four times the maximum recommended human oral dose, though this route and dose are not clinically relevant. 1
Human Pregnancy Data
Two studies in pregnant women have not shown that cyproheptadine increases the risk of abnormalities when administered during the first, second, and third trimesters of pregnancy, with no teratogenic effects observed in any newborns. 1
A case report documented successful use of cyproheptadine throughout pregnancy (continued until six weeks postpartum) in a woman with Cushing's syndrome, with normal fetal development initially reported. 2
Clinical Guidance
Despite the reassuring data, cyproheptadine should be used during pregnancy only if clearly needed, as the FDA label states that studies in humans cannot rule out the possibility of harm. 1
When antihistamines are necessary during pregnancy, the British Journal of Dermatology guidelines suggest avoiding all antihistamines when possible, especially in the first trimester, though none has been proven teratogenic in humans. 3
If antihistamine treatment is required, chlorphenamine is often chosen in the UK due to its long safety record, while loratadine and cetirizine are also FDA Pregnancy Category B drugs. 3
Important Precautions
Cyproheptadine has atropine-like (anticholinergic) effects and should be used with caution in patients with bronchial asthma, increased intraocular pressure, hyperthyroidism, cardiovascular disease, or hypertension. 1
The drug may cause sedation and diminish mental alertness, or conversely produce excitation particularly in young children. 1
Breastfeeding Considerations
- It is not known whether cyproheptadine is excreted in human milk. A decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother. 1