What is Teratogenic?

Teratogenic means a substance causes birth defects when the mother is exposed during pregnancy. Relevant to skincare: all topical retinoids (retinol, retinaldehyde, tretinoin, adapalene, tazarotene, retinyl palmitate, HPR) are teratogenic and contraindicated in pregnancy. Oral isotretinoin is Category X — absolutely contraindicated. Hydroquinone has high systemic absorption and is avoided in pregnancy. See the Pregnancy Safety Checker tool for a full list.