What side effects can verapamil cause?
Verapamil can cause both common, expected effects and less common but more serious reactions. Reported side effects include cardiovascular effects (because it slows heart rate and affects blood pressure), gastrointestinal symptoms, dizziness, and swelling. [1][2]
What are the most common side effects people report?
Common side effects can include dizziness, constipation, headache, and feeling tired. Some people also experience flushing or nausea. [1][2]
Can verapamil affect the heart rate or blood pressure?
Yes. Because verapamil slows conduction through the heart, it can cause symptoms related to a slower heart rate (bradycardia) or low blood pressure (lightheadedness, faintness). [1][2]
What are signs of serious side effects to watch for?
Seek urgent medical care if verapamil causes symptoms such as fainting, severe dizziness, chest pain, shortness of breath, or signs of an abnormal heartbeat. Allergic reactions (for example, swelling of the face or throat, hives, trouble breathing) are also emergency warning signs. [1][2]
Does verapamil cause swelling or constipation?
Swelling (such as swelling of the ankles/legs) can occur with verapamil, and constipation is a known issue for many people. These can be manageable but should be discussed with a clinician if they’re persistent or bothersome. [1][2]
How soon after starting verapamil do side effects happen?
Side effects can appear soon after starting or after dose increases, especially dizziness, fatigue, constipation, and blood-pressure-related symptoms. If symptoms are significant, clinicians may adjust the dose or formulation. [1][2]
What side effects are more likely if you take other medicines?
Verapamil interacts with several drugs, which can raise the risk of side effects like excessive slowing of the heart rate or low blood pressure, or increase verapamil levels. This is especially relevant with certain heart medications and other drugs that affect heart rhythm or metabolism. Check your specific medication list with a pharmacist or prescriber. [1][2]
When to contact a clinician vs. go to the ER
Contact a clinician promptly for side effects that are new, worsening, or affecting daily function (for example, persistent constipation, ongoing dizziness, or noticeable swelling). Go to the emergency department for fainting, severe lightheadedness, trouble breathing, allergic reaction symptoms, or chest pain. [1][2]
Sources
- https://www.nhs.uk/medicines/verapamil/side-effects/
- https://medlineplus.gov/druginfo/meds/a682620.html