Which medication is contraindicated due to its teratogenic effects during pregnancy?

Isotretinoin is well-known for its teratogenic effects, making it contraindicated during pregnancy. This medication, primarily used to treat severe acne, can cause severe birth defects, including teratogenic effects on the developing fetus. It affects the development of the heart, face, and central nervous system, leading to significant developmental abnormalities. Due to these risks, women of childbearing age are typically required to use effective contraception while using isotretinoin and to undergo regular pregnancy testing before, during, and after treatment.

In contrast, other medications listed have varying safety profiles during pregnancy. Acetaminophen is generally considered safe for use during pregnancy, commonly used for pain relief and fever reduction. Ibuprofen, while non-steroidal anti-inflammatory, is advised to be avoided particularly in the third trimester due to potential complications but does not carry the same level of risk as isotretinoin. Metformin is often used in pregnant women with diabetes or polycystic ovary syndrome and is considered relatively safe. Therefore, isotretinoin stands out as the medication with significant teratogenic risks, highlighting the importance of its contraindication in pregnant individuals.