Which condition is a contraindication of phenytoin?

• A. Pregnancy
• B. Hypertension
• C. Diabetes Mellitus
• D. Asthma

Answer: (A)

Phenytoin carries well-established teratogenic risks, so exposure during pregnancy is avoided whenever possible. It crosses the placenta and in early gestation can cause fetal hydantoin syndrome and other congenital abnormalities such as craniofacial defects and neural tube defects, with potential growth and developmental problems later on. Because of this, pregnancy is considered a contraindication to phenytoin; if seizure control is needed during pregnancy, safer alternatives like lamotrigine or levetiracetam are preferred, with appropriate folic acid supplementation prior to conception. In late pregnancy there’s also a risk of neonatal vitamin K deficiency and bleeding, which further supports avoiding phenytoin in pregnancy. The other conditions listed do not inherently make phenytoin unsafe on their own.