Does meclizine cause constipation? Exploring the side effects and management

October 13, 2025 •

4 min read

According to the National Institutes of Health, constipation is a known and common side effect associated with the use of meclizine, a first-generation antihistamine. This article delves into why meclizine cause constipation, examines who is most susceptible, and provides actionable steps for managing this unwelcome symptom.

Quick Summary

Meclizine, an antihistamine for motion sickness and vertigo, can cause constipation by slowing intestinal muscle contractions due to its anticholinergic effects. Managing it often involves dietary changes and staying hydrated, while those at higher risk, like older adults, may need closer monitoring or different medication.

Key Points

Anticholinergic Action: Meclizine causes constipation by blocking acetylcholine, which slows the muscle contractions in the digestive tract necessary for bowel movements.
Slower Motility: The decrease in intestinal movement leads to the colon reabsorbing more water, resulting in harder, drier, and more difficult-to-pass stool.
Increased Risk in Older Adults: Individuals over 65 are particularly susceptible to meclizine's anticholinergic effects, including confusion, dry mouth, and constipation.
Manage with Hydration and Fiber: Lifestyle changes such as increasing water intake, adding fiber to your diet, and regular exercise can effectively prevent and manage constipation caused by meclizine.
OTC Options Available: Over-the-counter remedies like osmotic (e.g., Miralax) and stimulant (e.g., Senokot) laxatives are effective for managing medication-induced constipation when lifestyle changes are not enough.
Consider Alternatives: Other motion sickness medications, like dimenhydrinate or scopolamine, also have anticholinergic effects, but their side effect profiles differ and should be discussed with a doctor.
Avoid Bulk Laxatives: Fiber-based laxatives like Metamucil are not recommended for medication-induced constipation and can sometimes make it worse.

Meclizine, a widely used over-the-counter and prescription medication, is primarily prescribed for the prevention and treatment of motion sickness, as well as the management of vertigo. While effective in calming the inner ear and reducing dizziness and nausea, its pharmacological properties can lead to several unwanted side effects. The potential for meclizine cause constipation is a well-documented issue stemming from its specific mechanism of action.

The anticholinergic effect and its impact on digestion

To understand why meclizine can cause constipation, it's essential to look at its classification. Meclizine is a first-generation antihistamine with central anticholinergic properties. Anticholinergic drugs work by blocking the action of acetylcholine, a neurotransmitter that plays a crucial role in the body, including stimulating muscle contractions in the digestive tract.

Slowing intestinal motility: Acetylcholine signals the smooth muscles of the intestines to contract, a process known as peristalsis, which moves stool through the digestive system. When meclizine blocks these signals, the rate of peristalsis slows down significantly.
Increased water absorption: A slower movement of stool means the colon has more time to reabsorb water from the waste material. This results in stool that becomes harder, drier, and more difficult to pass, which is the definition of constipation.

This anticholinergic effect is the primary reason behind meclizine-induced constipation, a side effect also common to many other first-generation antihistamines.

Risk factors for meclizine-induced constipation

While anyone taking meclizine can experience constipation, certain groups may be at a higher risk due to various factors. These include:

Older adults: Individuals aged 65 and older are identified by the American Geriatrics Society's Beers Criteria as being at a higher risk for adverse anticholinergic effects. Older adults may have reduced clearance of the drug, and their gastrointestinal system may already be slower. The combined effect increases the likelihood of constipation.
Dehydration: Insufficient fluid intake can exacerbate the effects of meclizine. When the body is dehydrated, the colon draws more water from the stool, making constipation more severe.
Poor dietary fiber intake: A diet low in fiber, a key component for healthy bowel movements, can increase the risk of constipation, especially when combined with a constipating medication like meclizine.
Concurrent use of other medications: Taking other medications with anticholinergic properties, such as certain antidepressants, bladder control medications, and antipsychotics, can compound the effect and increase the total anticholinergic burden on the body.
Pre-existing medical conditions: Conditions that affect gastrointestinal motility or urinary function, like an enlarged prostate or irritable bowel syndrome, can make individuals more prone to meclizine's side effects.

Managing and preventing constipation from meclizine

If you experience constipation while taking meclizine, several strategies can help alleviate the discomfort and prevent further issues. These include both lifestyle adjustments and potential over-the-counter (OTC) treatments.

Lifestyle modifications

Increase fluid intake: Drinking plenty of water throughout the day is crucial for keeping stool soft and promoting regular bowel movements.
Boost dietary fiber: Incorporate more fiber-rich foods into your diet, such as fruits, vegetables, beans, and whole grains.
Stay physically active: Regular exercise helps stimulate bowel activity and encourages stool to move through the digestive tract more efficiently.

Over-the-counter options

Stool softeners: These products, like docusate sodium, increase the amount of water in the stool, making it softer and easier to pass. They are not the best choice for established medication-induced constipation but can help prevent it when started early.
Osmotic laxatives: These laxatives, which include polyethylene glycol (Miralax) and magnesium hydroxide (Milk of Magnesia), work by drawing water into the colon to soften the stool.
Stimulant laxatives: For more stubborn cases, stimulant laxatives containing senna or bisacodyl stimulate the intestinal muscles to encourage a bowel movement. These work more quickly but can cause cramping.

Comparison of motion sickness medications

When considering options for motion sickness or vertigo, it's helpful to compare the potential for constipation and other side effects across different medications.


Feature	Meclizine	Dimenhydrinate (Dramamine Original Formula)	Scopolamine (Transderm-Scop)
Drug Class	First-Generation Antihistamine	First-Generation Antihistamine	Anticholinergic
Mechanism	Antihistaminic and Anticholinergic	Antihistaminic and Anticholinergic	Blocks acetylcholine in the brain
Constipation Risk	Common due to anticholinergic effects	Common due to anticholinergic effects	Common and potentially severe anticholinergic effects
Onset of Action	About 1 hour	Varies, can be quicker than meclizine	4 hours (patch)
Duration of Action	8 to 24 hours	4 to 6 hours	Up to 72 hours (patch)
Common Side Effects	Drowsiness, dry mouth, blurred vision	Drowsiness, dry mouth, blurred vision	Dry mouth, blurred vision, dizziness
Other Considerations	Generally less sedating than dimenhydrinate	More sedating than meclizine	Longer-lasting, applied as a patch; avoid in those with glaucoma

Conclusion

While meclizine is an effective treatment for motion sickness and vertigo, it's important to be aware of its potential to cause constipation due to its anticholinergic properties. This side effect is particularly concerning for older adults and can be exacerbated by dehydration and a low-fiber diet. By implementing lifestyle changes such as increasing fluid and fiber intake and exercising regularly, many individuals can manage or prevent this issue. For persistent or severe cases, discussing over-the-counter options like osmotic or stimulant laxatives with a healthcare provider is recommended. Being informed about this common side effect allows for more proactive management and a better overall treatment experience.

For more detailed information on managing medication-induced constipation, consult resources like the BC Cancer guide on the topic.

Frequently Asked Questions

Constipation is a common side effect of meclizine, with product information and health sources confirming its association with the medication due to its anticholinergic properties.

Meclizine is a first-generation antihistamine with anticholinergic effects, which means it blocks the neurotransmitter acetylcholine. This slows down the muscle contractions in the intestines, causing stool to move more slowly and become drier.

Yes, you can take preventive measures such as ensuring adequate fluid intake, consuming a diet rich in fiber, and engaging in regular physical activity.

Yes, older adults are considered to be at a higher risk. The American Geriatrics Society's Beers Criteria recommends caution with medications like meclizine in this age group due to their potent anticholinergic effects, which increase the risk of side effects like constipation.

For mild cases, increasing fiber and water may be sufficient. If not, osmotic laxatives (e.g., Miralax) or stimulant laxatives (e.g., Senokot) can be effective. Talk to a pharmacist or doctor to choose the best option.

No, bulk-forming laxatives are generally not recommended for medication-induced constipation, as they can sometimes worsen the condition by adding bulk to already sluggish bowels. Osmotic or stimulant laxatives are typically more effective.

You should contact a healthcare provider if your constipation does not improve with lifestyle changes or OTC medications, if it becomes severe, or if you suspect a more serious issue like a bowel obstruction.

Many motion sickness medications, particularly first-generation antihistamines like meclizine and dimenhydrinate, share anticholinergic properties that can lead to constipation. However, the severity of this effect can vary between drugs and individuals.