Verapamil is a calcium channel blocker that relaxes heart and blood vessel muscles.  Verapamil is used to treat hypertension, angina, and some heart rhythm disorders. The injected form of verapamil can be used to rapidly or temporarily restore normal heart rhythm.

Verapamil injection is usually provided by a health-care provider in an emergency situation. Oral verapamil is taken by mouth and should not be taken in larger or smaller quantities than prescribed or for longer than prescribed. 

Verapamil should not be used by those who have serious heart conditions, “sick sinus syndrome,” “AV block” without a pacemaker, severe heart failure, Wolff-Parkinson-White, Lown-Ganong-Levine syndrome, or slow heartbeats that have caused fainting. Inform your doctor of all your medical conditions, especially if you have congestive heart failure, hypotension, kidney or liver disease, a nerve-muscle disorder, or if you become pregnant. Do not breast-feed. Verapamil overdose may be fatal. Avoid alcohol and grapefruit products. Avoid getting up too quickly. Avoid activities that require alertness until you know how this medicine affects you.

Get emergency help if you suspect an overdose or allergic reaction. Contact your doctor at once if you experience a serious side effect such as: chest pain, fast/slow heart rate, lightheadedness, shortness of breath, fever, upper stomach pain, general malaise, lung problems, anxiety, pale skin, foamy mucus. Other side effects may include nausea and constipation, headache, dizziness, and abnormal liver function tests. Verapamil may interact with many drugs, so tell your doctor all other drugs you take, especially St. John’s wort, other heart or blood pressure medications, antibiotics, antifungals, antivirals, beta blockers, and more.