Verapamil for Migraine Prevention

Verapamil is a medication sometimes prescribed to prevent migraine headaches. Available as a generic product and under brand names Calan and Verelan, verapamil is in a class of drugs called calcium channel blockers that primarily are used to treat high blood pressure, angina, irregular heart rate, and other cardiac conditions.

Verapamil is rarely among the first drugs prescribed to prevent migraines, and it has not been approved by the U.S. Food and Drug Administration for this use. However, it may be prescribed off-label when other medications don't work. It is also used off-label for the prevention of cluster headaches, If your healthcare provider suggests you try verapamil, here's what you should know.

How It Works

Like all calcium channel blockers, verapamil allows smooth muscles to relax by preventing calcium from entering smooth muscle cells. Large blood vessels have smooth muscles in their walls, so smooth muscle relaxation prevents these blood vessels from constricting (narrowing). This is why these medications are theorized to help prevent migraines.

However, according to the National Headache Foundation, "recent genetic studies have suggested that calcium channels in the nervous system may not function normally in migraine." In other words, despite the effect calcium channel blockers have on the cells of cardiac blood vessels, the same effects may not apply to those of the nervous system.  

In the guidelines for managing migraines issued in 2012 by the American Academy of Neurology and the American Headache Society, verapamil ranks as a level U drug for migraine prevention, meaning there is “insufficient data to support or refute use for migraine prophylaxis.” This suggests that studies of the drug were flawed or that the results from multiple studies conflicted.

Dosage

Verapamil comes as a tablet, an extended-release (long-acting) tablet, and an extended-release (long-acting) capsule.

The dose prescribed for preventing migraines varies from 120 milligrams (mg) to 480 mg per day; the average dose is 240 mg. Finding the dose works is based could take time.

To hone in on the ideal dose for a headache patient, a healthcare provider will first prescribe the lowest dose possible, increasing it every two to four weeks until the benefits set in or side effects occur that make it intolerable. 

It can take two or three months for any migraine preventive medication to start to work. It's usually advisable to try to taper (gradually reduce) this drug after a year of being migraine-free, though you should only do so as directed by your practitioner.

Side Effects

Like all drugs, verapamil may cause adverse effects.

The most common include:

• Constipation
• Headache
• Swelling in the ankles and lower legs
• Dizziness
• Nausea
• Low blood pressure
• Fatigue

Verapamil has also been associated with more serious adverse effects, including heart failure, severe low blood pressure, an increase in liver enzymes, and heart blocks.

Interactions

If your healthcare provider recommends you try verapamil, it's important to make certain they are aware of any other medications, including over-the-counter drugs, and supplements your take on a regular basis. It may be that you should not take verapamil at all or that you will need to be carefully monitored.

Likewise, let your practitioner know if you take any herbal supplements, especially St. John's wort, which can cause verapamil to be less effective. By contrast, grapefruit juice may increase the level of verapamil in the bloodstream, which could lead to side effects.

Finally, when taking the verapamil, it's best not to drink alcohol or to cut back considerably if you tend to drink a lot, as the drug blocks the elimination of alcohol in the body. This could lead to increased alcohol levels in the bloodstream, a dangerous possibility that could cancel out the benefits of the medication.

Contraindications

Verapamil is not always an ideal or even safe option for migraine prevention.

People who should not take verapamil are those with various heart conditions such as:

• Low blood pressure (hypotension)
• Sick sinus syndrome (unless a pacemaker is in place)
• Second or third-degree heart block (unless there's a pacemaker)
• Atrial flutter or atrial fibrillation

Due to a lack of safety data, caution is advised on the use of verapamil for new moms who are breastfeeding. Women who are pregnant should only take this medication if the potential benefit of doing so outweighs the potential risk to the baby.