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nifedipine vs phenytoin

Side-by-side comparison of nifedipine and phenytoin. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.

moderate Known Drug Interaction

Co-administration of nifedipine with phenytoin, an inducer of CYP3A4, lowers the systemic exposure to nifedipine by approximately 70%. Avoid co-administration of nifedipine with phenytoin or any known CYP3A4 inducer or consider an alternative antihypertensive therapy.

Recommendation: Avoid taking these two drugs together. Your doctor may need to switch you to a different blood pressure medication.

Drug Class
nifedipine Calcium Channel Blocker
phenytoin Anticonvulsant (Hydantoin)
Type
nifedipine Prescription
phenytoin Prescription
Summary
nifedipine

Nifedipine is a calcium channel blocker. It helps to relax blood vessels, which can lower blood pressure and reduce chest pain.

phenytoin

Phenytoin injection is used to treat certain types of seizures. It can also prevent seizures during or after neurosurgery.

What It Treats
nifedipine

This medicine treats chest pain (angina) caused by tight blood vessels. It also treats high blood pressure. Lowering blood pressure reduces the risk of strokes and heart attacks.

phenytoin

This medicine treats generalized tonic-clonic status epilepticus, a type of prolonged seizure. It also helps prevent and treat seizures that may happen during or after brain surgery. Sometimes, it can be used for a short time instead of the oral form of phenytoin when you cannot take the medicine by mouth.

How It Works
nifedipine

Nifedipine blocks calcium from entering heart and blood vessel cells. This relaxes and widens blood vessels. As a result, the heart doesn't have to work as hard, and blood pressure goes down.

phenytoin

Phenytoin works by slowing down the signals in the brain that cause seizures. It stabilizes nerve cell membranes, reducing excessive electrical activity. This helps to prevent seizures from starting or spreading.

Common Side Effects
nifedipine
  • Swelling, especially in the legs or ankles
  • Headache
  • Fatigue
  • Dizziness
  • Constipation
phenytoin

No common side effects listed.

FAERS Reports
nifedipine
  • Difficulty breathing 2,429
  • Tiredness 2,303
  • Diarrhea 2,265
  • Feeling sick to your stomach 2,220
  • Headache 1,996
phenytoin
  • The medicine is reacting with another medicine 1,547
  • Seizure 1,382
  • Poisoning from different substances 1,353
  • Convulsion 1,260
  • Prolonged seizure 790
Serious Warnings
nifedipine

In rare cases, nifedipine can cause serious gastrointestinal problems, including obstruction. If you experience severe abdominal pain, vomiting, or inability to pass stool, seek immediate medical attention.

phenytoin

This medicine can cause serious heart problems if given too quickly. The injection rate should not be faster than 50 mg per minute for adults, and 1 to 3 mg/kg/min (or 50 mg per minute, whichever is slower) for children. Your heart will be monitored closely during and after the injection.

Pregnancy
nifedipine

Tell your doctor if you are pregnant or plan to become pregnant. It is not known if nifedipine will harm your unborn baby. Talk to your doctor about the risks and benefits of taking this medicine while pregnant or breastfeeding.

phenytoin

Taking phenytoin during pregnancy may increase the risk of birth defects. If you are pregnant or plan to become pregnant, talk to your doctor about the risks and benefits of this medicine.

Also Compare, Nearby Drugs

How to Read This nifedipine vs phenytoin Comparison

nifedipine is classified in the Calcium Channel Blocker drug class, while phenytoin sits within the Anticonvulsant (Hydantoin) class. Drugs from different classes work through distinct mechanisms, so a head-to-head comparison illustrates trade-offs rather than equivalence. Both drugs are prescription-only, so a licensed provider must authorize use.

Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, nifedipine has 11,213 submissions while phenytoin has 6,332. Those figures reflect cumulative reporting volume, not per-patient risk, so older, widely dispensed drugs typically look worse on count alone. These two drugs have a known moderate interaction flagged in FDA labeling, attributed to phenytoin makes your body get rid of nifedipine much faster than normal. this prevents the blood pressure medicine from working as well as it should.. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.

A table cannot substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between nifedipine and phenytoin - always consult your physician or pharmacist first.

Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.