Yes, verapamil causes constipation more often than almost any other blood pressure medication. In clinical trials, roughly 7% to 13% of people taking verapamil developed constipation, compared to just 1% to 3% on placebo. It is the most frequently reported side effect of the drug, though it’s usually mild and manageable.
How Common It Is
The exact rate depends on the dose and formulation. FDA labeling for the extended-release version reports constipation in 11.7% of patients across all doses studied, dropping to about 7.2% at the typical 240 mg daily dose. A larger pooled analysis of over 1,000 patients found an overall rate of 13%. By comparison, placebo groups consistently showed constipation rates of only 1% to 2%.
Age matters. People over 65 experience constipation from verapamil at slightly higher rates than younger adults. This is partly because older adults are already more prone to slower bowel transit, and the drug amplifies that tendency.
Why Verapamil Slows Your Bowels
Verapamil works by blocking calcium channels in muscle cells. That’s how it lowers blood pressure and slows heart rate: it prevents calcium from entering the cells that make blood vessels and heart muscle contract. The problem is that the same type of calcium channel exists in the smooth muscle lining your intestines. When verapamil blocks calcium entry there, the muscles that normally push food through your digestive tract contract less forcefully. Everything moves more slowly, and stool has more time to lose water, making it harder and more difficult to pass.
This isn’t an occasional quirk. It’s a direct, predictable consequence of how the drug works. The effect is dose-dependent: higher doses block more calcium channels in the gut, producing more constipation.
Dose Matters
The relationship between dose and constipation risk is well established. At 240 mg daily, about 7% of patients report it. As the dose climbs toward 360 mg or 540 mg, the incidence rises toward 13% or higher. If you’re on a lower dose and your doctor increases it, constipation may appear for the first time or get noticeably worse.
The FDA notes that constipation from verapamil is “typically mild, easily manageable, and the incidence usually diminished within about one week.” So for many people, the bowels adjust somewhat after the initial change, though not everyone experiences that improvement.
Verapamil vs. Other Calcium Channel Blockers
Not all calcium channel blockers carry the same risk. Verapamil causes significantly more constipation than its alternatives. Diltiazem, the other non-dihydropyridine calcium channel blocker, produces constipation in about 2% to 4% of patients. That’s roughly a third to a half the rate seen with verapamil. The dihydropyridine class (which includes amlodipine and nifedipine) generally causes even less.
This difference is large enough to influence prescribing decisions, especially for people who already struggle with constipation. If you’re taking verapamil and constipation is significantly affecting your quality of life, switching to a different calcium channel blocker or another class of blood pressure medication is a reasonable conversation to have with your prescriber.
Managing Constipation While on Verapamil
If the constipation is mild, simple measures often help. Increasing your fiber intake through fruits, vegetables, and whole grains can counteract some of the slowed transit. Staying well hydrated matters more than usual because your colon is absorbing extra water from stool that’s sitting there longer. Regular physical activity also stimulates intestinal motility.
Over-the-counter options like osmotic laxatives (the kind that draw water into the bowel) or stool softeners can be effective for constipation that doesn’t respond to diet and hydration alone. Stimulant laxatives work faster but aren’t ideal for daily long-term use.
For people who find constipation persistent and bothersome despite these steps, the most effective solution is often a medication change rather than layering on more remedies. Since the constipation is a direct pharmacological effect of verapamil, it won’t fully resolve as long as you’re taking the drug. Some people tolerate it easily; others find it genuinely disruptive, particularly those who were already prone to constipation before starting verapamil.