Based on NIH | Can amlodipine cause constipation, and how common is this side effect?

Amlodipine can cause constipation, though it is generally not among its most common side effects and appears to be relatively uncommon compared with effects like leg swelling (edema) and headache. ^[1] Amlodipine’s official prescribing information lists constipation among reported gastrointestinal adverse reactions. ^{[2] [3] [4] [5] [6]}

What the official labeling says

Constipation is included in the gastrointestinal side effects reported with amlodipine (often alongside diarrhea, dyspepsia/indigestion, flatulence, and dysphagia). ^[1] This listing indicates the event has been observed in patients, although the label does not provide a precise percentage for constipation itself. ^[2] In contrast, the label does provide dose‑related rates for more common effects like edema, showing 1.8% at 2.5 mg, 3.0% at 5 mg, and 10.8% at 10 mg versus 0.6% with placebo, highlighting that constipation is not among the top dose‑dependent adverse events. ^{[7] [8]}

How common is constipation with amlodipine?

In pooled clinical trial safety summaries, amlodipine’s overall discontinuation due to side effects is about 1.5%, similar to placebo, with edema and headache being the most frequent issues mentioned; constipation is listed but not emphasized with a specific rate, suggesting it occurs but less commonly. ^{[7] [9]} Comparisons within calcium channel blockers show constipation is notably more common with verapamil, while amlodipine’s signal for constipation is weaker in controlled data. ^[10] Observational data have suggested constipation may occur more often in people taking amlodipine alone than in those taking it with atenolol, though the study was small and the confidence interval was wide, so this finding should be interpreted cautiously. ^[11]

Summary of frequency signals

• Constipation is a recognized adverse effect of amlodipine, but exact incidence is not specified in most labeling summaries. ^{[1] [2]}
• Edema and headache are much more commonly reported and show clear dose relationships; constipation does not show that same dose-related prominence in trial data. ^[7]
• Compared with some other calcium channel blockers (especially verapamil), amlodipine appears less associated with troublesome constipation. ^[10]

Why calcium channel blockers may cause constipation

Calcium channel blockers reduce calcium entry into smooth muscle, which can decrease contractions of the gastrointestinal tract and slow motility; this mechanism has been demonstrated with agents in the class, leading to reduced colonic contractile activity in animal and in vitro models. ^{[12] [13]} Reduced GI motility can manifest clinically as constipation in susceptible individuals. ^[12]

Practical takeaways

• If constipation occurs after starting amlodipine, it is a plausible medication side effect, although it tends to be less common than swelling or headache. ^{[1] [7]}
• The effect may relate to decreased gut smooth‑muscle contractions associated with the drug class. ^[12]
• Amlodipine’s overall tolerability is favorable, and constipation is typically mild; persistent or severe symptoms warrant discussion with a clinician to consider dose adjustments or alternative therapies, especially if other causes are excluded. ^{[7] [10]}

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Quick comparison table

Item	Amlodipine labeling mentions	Notes on frequency
Constipation	Yes (listed among GI adverse reactions) [1] [2] [3] [4] [5] [6]	No precise percentage given; considered less common than edema/headache in trial summaries. [7]
Edema (leg swelling)	Yes, dose‑related rates provided (up to ~10.8% at 10 mg) [7] [8]	Most common side effect and dose‑dependent. [7]
Headache	Common, noted across trials [7] [9]	Among top reported adverse effects. [7]
Comparison to verapamil	Constipation more prominent with verapamil than amlodipine in comparative data. [10]	Class effect varies by agent. [10]

In short, constipation can occur with amlodipine but is typically less frequent than its hallmark side effects like edema; mechanistically, reduced GI smooth‑muscle activity underlies this potential reaction. ^{[1] [7] [12] [10]}