Can amlodipine cause constipation in a 42‑year‑old woman with well‑controlled hypertension and normal thyroid‑stimulating hormone level?

Can Amlodipine Cause Constipation?

Yes, amlodipine can cause constipation, though this adverse effect is less commonly recognized than peripheral edema. 1

Evidence for Amlodipine-Induced Constipation

• An observational study of 100 hypertensive patients demonstrated that those taking amlodipine alone had a 4-fold increased relative risk (RR 4.00,95% CI 0.89–17.92) of developing constipation compared to patients on combination therapy with amlodipine plus atenolol. 1

• Experimental studies on isolated rabbit intestine showed that amlodipine dose-dependently inhibits spontaneous intestinal activity, providing a mechanistic explanation for constipation. 1

• In comparative safety data from 4,227 subjects, constipation was more common with verapamil than amlodipine, suggesting that while amlodipine can cause constipation, it does so less frequently than non-dihydropyridine calcium channel blockers. 2

Clinical Context for This Patient

For a 42-year-old woman with well-controlled hypertension and normal thyroid function:

• Thyroid dysfunction has been appropriately ruled out as a cause of constipation, since hypothyroidism is a common reversible etiology. 3

• The patient's age and gender place her in a demographic where amlodipine is generally well-tolerated for cardiovascular outcomes, though women have a 2.6-fold higher risk of amlodipine-induced peripheral edema compared to men. 4

Management Algorithm When Constipation Occurs

If constipation is attributed to amlodipine, switching to an alternative antihypertensive is the most appropriate strategy:

1. First-line alternative: Thiazide diuretics (chlorthalidone 12.5–25 mg or hydrochlorothiazide 25–50 mg daily) provide effective blood pressure control without causing constipation. 5

2. Second alternative: ACE inhibitor plus thiazide combination (e.g., lisinopril 10–40 mg with a thiazide) is evidence-based and does not increase constipation risk. 5

3. Avoid non-dihydropyridine calcium channel blockers (diltiazem, verapamil), as these agents cause more constipation than amlodipine and have negative inotropic effects. 4, 2

Common Pitfalls to Avoid

• Do not empirically add laxatives while continuing amlodipine without first considering medication substitution, as this addresses the symptom rather than the cause. 3

• Do not assume all calcium channel blockers have equal constipation risk—verapamil causes significantly more constipation than dihydropyridines like amlodipine. 2

• Assess for other constipating medications including antacids, anticholinergics, antidepressants, and opioids before attributing constipation solely to amlodipine. 3

Relative Frequency of Amlodipine Side Effects

While amlodipine's most common adverse effect is peripheral edema (particularly in women and elderly patients), constipation is a recognized but less frequent side effect. 2, 6 The overall safety profile of amlodipine remains favorable, with severe side effects occurring at approximately half the rate seen with beta-blockers. 2