Nifedipine: uses, side effects and cautions

The NHS says nifedipine is used to treat high blood pressure, angina, and Raynaud phenomenon, a condition that stops blood flowing properly to the fingers and toes. It is a calcium channel blocker that works by relaxing and widening the blood vessels. It comes as capsules or tablets that you swallow, and the NHS names the brands Coracten and Nifedipress.

UK product information for one modified-release capsule describes its licensed uses as treating hypertension and preventing chronic stable angina in adults.

Nifedipine products are not all the same. The NHS says you take it one to three times a day, depending on the type of capsule or tablet you have. Modified-release products release the drug slowly, so they are taken less often than short-acting ones. Keep to the product and schedule on your label, and ask the pharmacist before accepting a different brand.

For the modified-release capsule whose product information we reviewed, the starting dose is one 30 mg capsule daily, adjustable by the prescriber up to a stated maximum, taken at the same time each day, preferably in the morning, with capsules swallowed whole at 24-hour intervals. Other products differ.

It can be taken with or without food. If you miss a dose, take it as soon as you remember, then wait at least 12 hours before the next dose, and never take two at the same time. Taking an extra dose can be dangerous, so call NHS 111 if you exceed your prescribed dose, and do not drive yourself if you feel unwell.

The NHS says nifedipine may not be suitable if you have ever had an allergic reaction, low blood pressure, a heart condition, unstable angina, diabetes, or a severe liver or kidney condition. Product information also lists aortic stenosis, a recent heart attack, cardiogenic shock and acute porphyria among contraindications, and says patients with diabetes may need their diabetes treatment adjusted.

Common effects are headaches, flushing, generally feeling unwell, constipation and swollen ankles. Product information also notes palpitations, a fast heartbeat and low blood pressure, and that dizziness, lethargy and visual disturbances can affect driving and machinery.

Serious effects include anaphylaxis, a faster heartbeat and shortness of breath or difficulty breathing; call NHS 111 if you are worried, and 999 for signs of a severe allergic reaction.

Do not eat grapefruit or drink grapefruit juice with nifedipine because it increases the chance of side effects; product information says grapefruit juice can raise blood levels. Alcohol can lower blood pressure further.

The NHS says nifedipine can interact with other blood pressure medicines, some antibiotics, stomach ulcer medicines, heart medicines, epilepsy medicines and antifungals. Product information adds that macrolide antibiotics, protease inhibitors and azole antifungals raise nifedipine levels while rifampicin reduces its effect, and that beta blockers should be withdrawn gradually rather than abruptly.

The NHS says you can usually take nifedipine if you are pregnant or breastfeeding, but should consult a healthcare professional. The manufacturer information for the one modified-release capsule we reviewed is more cautious and lists pregnancy and breastfeeding as contraindications. Because the two sources differ, any decision about nifedipine in pregnancy belongs with your specialist or prescriber. Report suspected side effects via the Yellow Card scheme.