Does Hydroxychloroquine Cause Diarrhea? Understanding and Managing Gastrointestinal Side Effects

October 11, 2025 •

3 min read

According to research, gastrointestinal side effects, including diarrhea, affect a significant number of people who take the medication hydroxychloroquine. As one of the more common adverse reactions, understanding its frequency and management is key to successful treatment.

Quick Summary

Hydroxychloroquine, commonly used for autoimmune conditions, can cause diarrhea and other GI issues, particularly when treatment begins. Taking the medication with food, adjusting the dose, and staying hydrated are effective management strategies for these common, often temporary, side effects. Severe or persistent symptoms warrant immediate medical consultation.

Key Points

Common Side Effect: Diarrhea is one of the most common gastrointestinal side effects associated with hydroxychloroquine.
Initial Phase: GI symptoms, including diarrhea, are most likely to occur when first starting the medication as your body adjusts.
Take with Food: To minimize stomach upset and diarrhea, it is highly recommended to take hydroxychloroquine with a meal or a glass of milk.
Hydration is Key: Persistent diarrhea can lead to dehydration, so drinking plenty of fluids is important for management.
Seek Medical Advice: Contact your doctor if diarrhea is severe, persistent, or accompanied by other serious symptoms like fever, severe pain, or dehydration.

Hydroxychloroquine and its gastrointestinal impact

Hydroxychloroquine (brand name Plaquenil) is a disease-modifying antirheumatic drug (DMARD) used to treat conditions such as rheumatoid arthritis, lupus erythematosus, and malaria. While generally well-tolerated, it is known to cause a range of side effects, with gastrointestinal (GI) disturbances being among the most frequent. Nausea, abdominal pain, and vomiting are often reported alongside diarrhea. The incidence of these GI effects can range widely, with studies reporting figures anywhere from 7% to 37% of patients experiencing them.

These side effects most commonly occur during the initial phase of treatment as the body adjusts to the new medication. For many, the symptoms are mild and tend to diminish over time. However, some individuals may experience more persistent or severe symptoms that require medical attention or a change in their treatment plan.

Why does hydroxychloroquine cause diarrhea?

The exact mechanism by which hydroxychloroquine causes gastrointestinal upset is not fully understood. As a weakly basic agent, it can increase the pH of cellular compartments, which may interfere with cellular processes in the digestive tract. This can lead to digestive discomfort and changes in bowel habits, resulting in symptoms like nausea, cramps, and loose stools.

Strategies for managing diarrhea

For those who experience diarrhea or other GI symptoms, several simple yet effective strategies can help minimize discomfort and allow for continued treatment. These remedies can often be implemented with guidance from a healthcare provider.

How to take hydroxychloroquine to minimize side effects

One of the most effective ways to prevent GI issues is to adjust how and when you take your medication. Taking the dose with or immediately after a meal can significantly reduce stomach upset. If a single daily dose causes problems, a healthcare provider might approve splitting the daily amount into two smaller doses taken with breakfast and dinner. If you take antacids, be sure to separate the dose by at least four hours, as they can interfere with absorption.

Dietary and lifestyle adjustments

Stay hydrated: Diarrhea can lead to dehydration and electrolyte imbalance. It is crucial to drink plenty of fluids, such as water, broth, or low-sugar electrolyte drinks, to replenish what is lost.
Choose the right foods: Eating smaller, more frequent meals can be easier on the digestive system. A diet of bland, binding foods (e.g., bananas, rice, applesauce, toast) is often recommended, as it can help firm up stools.
Avoid trigger foods: High-fat, heavily spiced, or fried foods can worsen diarrhea. Caffeine and dairy products may also act as irritants for some individuals.
Consider dose adjustments: If symptoms are persistent, a doctor may recommend lowering the dose temporarily to see if the symptoms improve. In some cases, switching to a different medication may be necessary if diarrhea is severe or intolerable.

Comparison of mild vs. severe diarrhea

It is important to know the difference between common, manageable diarrhea and symptoms that indicate a more serious problem. The table below outlines key differences.


Symptom	Mild, Common Diarrhea	Severe, Concerning Diarrhea
Frequency	Occasional loose stools; may occur for the first few weeks of treatment.	Frequent, watery stools that last more than two days. More than six episodes in 24 hours.
Other GI Symptoms	Mild abdominal cramps, nausea that may resolve over time.	Severe abdominal pain and cramps. Persistent vomiting.
Stool Appearance	Normal color, loose consistency.	Contains blood, pus, or appears black and tarry.
Accompanying Symptoms	General fatigue or headache that improves with time.	Fever of 102°F or higher. Signs of dehydration (e.g., dizziness, lightheadedness, infrequent dark urination).

When to contact a healthcare provider

While mild diarrhea is often manageable at home, certain signs and symptoms require immediate medical consultation. You should contact your doctor if you experience:

Persistent or severe diarrhea that does not improve
Symptoms of dehydration, such as excessive thirst, dizziness, or reduced urination
Bloody, black, or tarry stools
Diarrhea accompanied by fever
Any severe or uncontrolled gastrointestinal symptoms

Conclusion

While it is a well-established fact that hydroxychloroquine can cause diarrhea and other GI side effects, these issues are often temporary and manageable with appropriate strategies. By taking the medication with food, staying hydrated, and making thoughtful dietary choices, many patients can continue their treatment with minimal disruption. It is essential to communicate any persistent or severe side effects to a healthcare provider to ensure safe and effective long-term therapy. For more details on the medication's overall safety profile, refer to guidelines from reputable sources, such as the American College of Rheumatology.

Frequently Asked Questions

Diarrhea is a relatively common side effect, with some studies indicating that up to 37% of patients experience gastrointestinal issues. However, the severity can vary, and symptoms often improve over time.

Taking hydroxychloroquine with food or milk is the best way to reduce gastrointestinal side effects like diarrhea. For example, taking your dose with breakfast or dinner can be effective.

You should not stop taking hydroxychloroquine without consulting your doctor. Mild diarrhea often resolves on its own. Your doctor may suggest strategies to manage the symptoms or adjust your dose.

Eating smaller, more frequent meals can help. Focus on bland, binding foods like rice, bananas, and toast. Avoid fatty, fried, and heavily spiced foods that can irritate the stomach.

You should always consult your healthcare provider before taking any other medications, including over-the-counter products like loperamide. They can advise if it is safe to do so in your specific case.

While most diarrhea from hydroxychloroquine is not serious, severe or persistent diarrhea can be a sign of a more serious issue. Look for warning signs like bloody stools, fever, or dehydration, and contact your doctor immediately if they occur.

For many people, the diarrhea and other GI symptoms are temporary and subside within the first few weeks of treatment as the body adjusts. If it persists, talk to your doctor about further management.