Can ACTEMRA Cause Diarrhea? Understanding the Risks and Management

October 10, 2025 •

4 min read

Clinical trials have shown that diarrhea is one of the most common adverse events seen in patients treated with intravenous ACTEMRA, particularly those with systemic juvenile idiopathic arthritis (SJIA). While often mild, this gastrointestinal side effect can sometimes signal a more serious underlying issue and warrants attention.

Quick Summary

ACTEMRA (tocilizumab) can cause diarrhea, an event documented in clinical studies as both a common side effect and a potential sign of serious gastrointestinal complications.

Key Points

Common Side Effect: Diarrhea is a known and relatively common side effect of ACTEMRA, reported in clinical trials, particularly in patients with SJIA.
Risk of Serious GI Complications: In rare cases, diarrhea can be a symptom of a serious gastrointestinal issue, such as a bowel perforation, especially in patients with diverticulitis.
Immunosuppression and Infection: The medication's immunosuppressive effects increase the risk of infections, including gastroenteritis, which can cause diarrhea.
Immediate Medical Attention: Seek immediate medical care if diarrhea is accompanied by fever, severe stomach pain, unusual changes in bowel habits, or blood in stool.
Management of Mild Symptoms: Mild diarrhea can often be managed with increased hydration and dietary changes, but always consult a healthcare provider before using any anti-diarrheal medication.
Watch for Infusion Reactions: For those on IV infusions, diarrhea can be an infusion-related reaction, occurring during or shortly after administration.

Can ACTEMRA Cause Diarrhea?

Yes, ACTEMRA (tocilizumab) can cause diarrhea, and it is a well-documented side effect. Data from clinical trials show that gastrointestinal issues, including diarrhea, occur in some patients taking the medication. While it can be a nuisance, understanding the potential causes, related risks, and appropriate management strategies is crucial for patient safety.

Diarrhea as a Common ACTEMRA Side Effect

Diarrhea has been identified as a common adverse event in multiple clinical trial settings for ACTEMRA:

Systemic Juvenile Idiopathic Arthritis (SJIA): In a 12-week controlled study, diarrhea was among the most common adverse events (at least 5%) in patients receiving intravenous ACTEMRA. Pediatric patients were also noted to experience diarrhea more frequently than adults.
Infusion-Related Reactions: For those receiving ACTEMRA via intravenous (IV) infusion, diarrhea has been reported as part of an infusion-related reaction that can occur during or within 24 hours of the infusion. Other symptoms can include rash, headache, and nausea.
General Clinical Trials: Overall drug safety profiles across various conditions treated by ACTEMRA, such as rheumatoid arthritis (RA), also list diarrhea as a possible side effect, ranging from common to less frequent depending on the trial and patient group.

Potential Causes of Diarrhea with ACTEMRA

The diarrhea experienced by patients on ACTEMRA can stem from several different causes, ranging from the drug's immunosuppressive action to more serious, albeit rare, complications.

Increased Risk of Infection

As an immunosuppressant, ACTEMRA works by blocking the inflammatory cytokine interleukin-6 (IL-6). This action can weaken the immune system, making patients more susceptible to infections. Gastrointestinal infections, like gastroenteritis, are a potential consequence of this immunosuppression and can lead to diarrhea. Symptoms of infection, such as fever, chills, and diarrhea, should always be reported to a healthcare provider.

Serious Gastrointestinal Complications

In rare cases, diarrhea and abdominal pain can be symptoms of a more serious gastrointestinal event, such as a bowel or stomach perforation. This is particularly a risk for patients with a history of diverticulitis or ulcers, or those also taking NSAIDs, corticosteroids, or methotrexate. Patients should be monitored for new or worsening abdominal symptoms and changes in bowel habits. A fever combined with persistent stomach pain and altered bowel habits warrants immediate medical evaluation.

Concomitant Medication Use

Many patients taking ACTEMRA also take other medications for their underlying inflammatory condition. Some of these, such as nonsteroidal anti-inflammatory drugs (NSAIDs), can exacerbate or increase the risk of gastrointestinal issues. The cumulative effect of multiple medications can contribute to diarrhea and other digestive problems.

Comparison of Diarrhea-Related Side Effects with ACTEMRA

To help distinguish between mild, manageable diarrhea and a more serious condition, the following table compares key characteristics.


Feature	Typical, Mild Diarrhea	Potentially Serious Gastrointestinal Event
Onset	Can occur anytime, sometimes soon after infusion.	Can develop at any point during treatment, sometimes alongside systemic symptoms.
Severity	Often self-limiting, may be bothersome but not debilitating.	Characterized by severe stomach cramps, bloating, and persistent symptoms.
Associated Symptoms	May occur with other common side effects like headache, nasopharyngitis, or nausea.	Accompanied by fever, severe and new stomach pain, and significant changes in bowel habits. May include blood in stool, vomiting, or signs of infection.
Action Required	Focus on hydration; dietary modifications; consult doctor for persistent issues.	Contact your healthcare provider immediately. May require medication adjustment or urgent evaluation.

How to Manage Mild Diarrhea from ACTEMRA

For mild, non-severe cases of diarrhea, there are several steps that can help manage symptoms:

Stay Hydrated: Drink plenty of fluids, such as water, broth, or electrolyte drinks, to prevent dehydration.
Modify Your Diet: Avoid irritating foods such as spicy, high-fat, and high-fiber items. Stick to bland, low-fiber foods like the BRAT diet (bananas, rice, applesauce, toast) to ease digestive distress.
Monitor Symptoms: Keep a record of when the diarrhea occurs, its severity, and any other associated symptoms to discuss with your doctor.
Consult Your Doctor Before OTC Medications: Do not take over-the-counter anti-diarrheal medications without first speaking to your healthcare provider, as some can have interactions or mask serious symptoms.

When to Contact Your Doctor About Diarrhea

While mild diarrhea can be managed, certain symptoms associated with ACTEMRA-related gastrointestinal issues require prompt medical attention. Contact your doctor immediately if you experience any of the following:

Fever and Severe Abdominal Pain: These symptoms could indicate a serious infection or a bowel perforation.
Persistent Diarrhea: If diarrhea continues for more than a few days, even if mild, it's important to report it to your healthcare team.
Blood in Stool: Any sign of blood, or black and tarry-looking stools, could signal internal bleeding.
Unusual Fatigue or Signs of Infection: Since ACTEMRA can mask signs of infection, any unexplainable tiredness, chills, or muscle aches should be reported.
Significant Change in Bowel Habits: Be alert for any persistent new pattern in your bowel movements, which can be a warning sign.

Conclusion: Prioritizing Patient Safety

Can ACTEMRA cause diarrhea? The answer is definitively yes. As with any potent medication, it is essential for patients to be aware of the potential side effects. While mild diarrhea can be managed with supportive care, it is crucial to remain vigilant for signs of more serious complications, such as infections or gastrointestinal perforations. Open and continuous communication with your healthcare provider is the most effective way to manage side effects, ensure your safety, and achieve the best possible therapeutic outcomes.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Consult with a qualified healthcare professional regarding any medical concerns or before making any decisions related to your treatment.

Frequently Asked Questions

Diarrhea from ACTEMRA is not always serious, as it can be a common and mild side effect. However, when it occurs with other symptoms like fever, severe abdominal pain, or blood in your stool, it could signal a serious issue like an infection or a bowel perforation, and you should contact your doctor immediately.

Diarrhea has been noted as one of the most common adverse events in some clinical trials for ACTEMRA. For instance, it was reported in at least 5% of pediatric patients with SJIA treated with ACTEMRA-IV. The overall incidence can vary between patient populations and clinical trial designs.

You should not take any over-the-counter anti-diarrhea medicine without first consulting your doctor or pharmacist. It is important for your healthcare team to understand the cause of your diarrhea and approve any additional treatments.

If you experience mild diarrhea, you should focus on staying well-hydrated by drinking plenty of fluids. Consider following a bland diet, such as the BRAT diet, and avoid spicy or high-fat foods. If the diarrhea persists or worsens, contact your healthcare provider.

ACTEMRA suppresses the immune system by inhibiting interleukin-6. This can increase a patient's susceptibility to infections, including gastrointestinal infections like gastroenteritis, which can cause diarrhea.

Patients with a history of diverticulitis, ulcers, or those also taking NSAIDs, corticosteroids, or methotrexate are at a higher risk for serious gastrointestinal complications, such as perforations.

Diarrhea has been noted in patients receiving both intravenous (IV) and subcutaneous (SC) formulations. However, for IV administration, diarrhea can be part of an infusion-related reaction that occurs shortly after the infusion.