Can Azithromycin Cause Constipation? Understanding This Rare Side Effect

October 12, 2025 •

3 min read

While often associated with diarrhea, studies show that azithromycin can cause constipation, though it is a less frequent side effect, reported in a small percentage of patients. This confirms that for some, can azithromycin cause constipation? Yes, it is a possibility, albeit a relatively uncommon one.

Quick Summary

Azithromycin can cause constipation in a minority of patients, usually due to disruption of the gut microbiome. Lifestyle factors like dehydration and diet also contribute to this less common side effect.

Key Points

Possible but Not Common: Azithromycin can cause constipation, but it is a less frequent side effect than diarrhea.
Gut Microbiome Disruption: The primary reason for digestive side effects is the antibiotic's impact on the balance of beneficial gut bacteria.
Lifestyle Factors Play a Role: Constipation can be exacerbated by dehydration, lack of fiber, and reduced activity, often related to being ill.
Management is Key: Increasing fluids, dietary fiber, and light exercise are effective first-line strategies for relief.
Probiotics Can Help: Probiotics or fermented foods can aid in restoring gut health, but should be discussed with a doctor for proper timing.
Consult a Doctor for Persistent Issues: If constipation is severe, prolonged, or accompanied by other concerning symptoms, seek medical advice.

While azithromycin is an effective and widely-prescribed macrolide antibiotic, like many medications, it can come with side effects. Most commonly, these are gastrointestinal, and patients are more likely to experience diarrhea, loose stools, and stomach upset. However, a less common but reported side effect is constipation. Understanding the mechanisms behind this issue and how to manage it can help those undergoing treatment.

The Link Between Azithromycin and Constipation

All antibiotics, including azithromycin, can disrupt the balance of bacteria in the gut, known as the gut microbiome. This disruption can affect normal digestive function. Beneficial gut bacteria are crucial for breaking down food and maintaining intestinal health. When these bacteria are reduced by antibiotics, it can lead to changes in gut motility. While this often results in diarrhea, in some individuals, it can slow down digestion and cause constipation.

The Prokinetic Paradox

Azithromycin, a macrolide antibiotic, is generally considered to have weaker gut-stimulating effects compared to other macrolides like erythromycin. However, a specific metabolite of azithromycin, called deglycosylated azithromycin (Deg-AZM), has shown properties that can influence intestinal movement. Despite this, the overall effect of azithromycin on the gut is complex and can result in varied digestive symptoms in different people.

Other Factors Contributing to Constipation

Illness can also contribute to constipation through factors independent of medication:

Dehydration: Reduced fluid intake during illness can lead to harder stools.
Dietary Changes: A decrease in fiber intake, common during illness, can slow digestion.
Reduced Physical Activity: Less movement can also decrease gut motility.
Other Medications: Certain other drugs taken for illness symptoms may also cause constipation.

Managing Constipation During Azithromycin Treatment

If you experience constipation while on azithromycin, these strategies may help. Consult your healthcare provider before trying new remedies.

Increase Fluid Intake: Drink plenty of water to help soften stools.
Boost Your Fiber Intake: Eat more fiber-rich foods like fruits, vegetables, and whole grains. Introduce fiber gradually if your diet is typically low in it.
Stay Active: Gentle exercise, such as walking, can help stimulate bowel function.
Discuss Probiotics with Your Doctor: Probiotics may help restore gut bacteria balance. Talk to your doctor about whether and when to take them, usually a few hours before or after your antibiotic dose.
Over-the-Counter Relief: Your doctor might suggest a fiber supplement, stool softener, or mild laxative for temporary relief.

Comparison of Azithromycin and Common GI Side Effects


Side Effect	Incidence	Management Strategies
Constipation	Less common (up to 2% reported)	Increase fluids and fiber, light exercise. Consult doctor if persistent.
Diarrhea	Most common (up to 14% or more)	Stay hydrated, eat bland foods. Severe, watery, or bloody diarrhea requires immediate medical attention.
Nausea	Common (up to 18%)	Take medication with food. Eat smaller meals. Avoid greasy, spicy, or high-fat foods.
Abdominal Pain	Common (up to 7%)	Take with food. Contact doctor if pain is severe, persistent, or accompanied by other serious symptoms.

When to Contact a Healthcare Provider

Contact your doctor if you experience concerning symptoms:

Severe, bloody, or watery diarrhea
Persistent or worsening constipation
Severe abdominal pain or cramping
Signs of liver problems, like dark urine or yellowing of skin/eyes

Conclusion

To reiterate, can azithromycin cause constipation? Yes, it is a possible but uncommon side effect, primarily due to disrupting the gut microbiome. While diarrhea is more frequent, constipation can occur, sometimes influenced by illness-related factors like dehydration and reduced activity. Increasing fluids, fiber, and light exercise can help manage mild constipation. It is vital to complete your antibiotic course as directed and contact your doctor for persistent or severe symptoms. More information on azithromycin is available through MedlinePlus drug information.

Frequently Asked Questions

Diarrhea is a far more common gastrointestinal side effect of azithromycin than constipation. Studies indicate that while constipation may affect a very small percentage of users, diarrhea is reported much more frequently.

Azithromycin, like other antibiotics, disrupts the natural balance of beneficial bacteria in the gut, known as the gut microbiome. This imbalance can alter intestinal motility, which may slow down bowel movements and lead to constipation in some individuals.

You can take several steps to help prevent constipation. These include staying well-hydrated, eating fiber-rich foods like fruits and vegetables, and maintaining a regular, gentle exercise routine as tolerated.

It is best to consult your doctor or pharmacist before taking any over-the-counter laxatives or stool softeners. They can confirm that there are no interactions and recommend the most appropriate option for your situation.

Probiotics can help restore the balance of gut bacteria, potentially mitigating some digestive side effects. It's recommended to discuss with your doctor whether a probiotic supplement or consuming fermented foods like yogurt would be beneficial for you.

For most people, digestive issues caused by antibiotics are temporary and resolve shortly after the medication course is finished. However, the recovery of the gut microbiome can take some time, from weeks to months.

You should contact a healthcare provider if your constipation is severe, persistent, or accompanied by other concerning symptoms like severe abdominal pain, fever, or bloody stools. These could indicate a more serious condition.