Can Jakafi cause diarrhea? An In-Depth Look at This Common Side Effect

October 10, 2025 •

4 min read

Yes, Jakafi can cause diarrhea, and clinical trials have documented it as one of the more common non-hematologic side effects for patients with myelofibrosis and polycythemia vera. Managing this gastrointestinal symptom is an important part of maintaining quality of life while on treatment.

Quick Summary

Diarrhea is a recognized side effect of the medication Jakafi (ruxolitinib). It is often manageable with supportive care, dietary changes, and, in some cases, medication under medical supervision. The severity and incidence can vary among patients depending on their underlying condition and dosage.

Key Points

Diarrhea is a known side effect: Jakafi (ruxolitinib) is documented to cause diarrhea, which is a common non-hematologic side effect in patients with myelofibrosis and polycythemia vera.
Prevalence can vary: The reported frequency of diarrhea in clinical trials differs, with some studies showing an incidence ranging from approximately 12% to over 35% depending on the trial and duration of treatment.
Severity is often mild to moderate: In many cases, the diarrhea experienced by patients on Jakafi is not severe and can be managed effectively with supportive care.
Dietary changes are helpful: Adopting a bland diet and avoiding spicy, greasy, or high-fiber foods can help reduce symptoms.
Stay hydrated: It is crucial to drink plenty of fluids and consider electrolyte drinks to prevent dehydration from persistent diarrhea.
Consult your doctor before using OTC medications: While over-the-counter options like loperamide (Imodium) may be an option, always get your healthcare provider's approval first.
Report concerning symptoms: If diarrhea is severe, persistent for more than two days, or accompanied by fever or bloody stools, contact your medical team immediately.

Understanding Jakafi and Its Mechanism

Jakafi, known generically as ruxolitinib, is an oral medication classified as a Janus kinase (JAK) inhibitor. It is primarily prescribed for certain types of myelofibrosis, polycythemia vera, and graft-versus-host disease. Jakafi works by blocking the signals of specific enzymes, JAK1 and JAK2, which are overactive in these conditions and contribute to abnormal cell growth. While highly effective at managing symptoms associated with these blood disorders, this inhibition can also affect other systems in the body, including the gastrointestinal tract, leading to side effects like diarrhea.

How Common is Jakafi-Related Diarrhea?

Diarrhea is a frequently reported adverse event among patients taking Jakafi, although its specific incidence and severity can vary based on the treated condition. Clinical trials have provided insight into how common this side effect is across different patient populations:

Myelofibrosis and Polycythemia Vera: In studies like the COMFORT-II trial, diarrhea was among the most commonly reported non-hematologic side effects, with some long-term data reporting it in over a third of patients. However, in the JUMP trial, the incidence of any-grade diarrhea was reported at 12.5%. Often, these gastrointestinal issues are classified as mild to moderate.
Acute Graft-Versus-Host Disease (aGVHD): The incidence of specific non-hematologic side effects can differ in aGVHD, but gastrointestinal symptoms, including diarrhea, are possible and need monitoring.

The frequency and severity can be influenced by factors like the dosage, the patient’s overall health, and the presence of other medical conditions.

Managing Diarrhea from Jakafi

While diarrhea can be disruptive, there are several effective strategies for managing it. It is crucial to work closely with your healthcare provider to develop a plan that is right for you, as they can assess the cause and severity.

Dietary Modifications

Changes to your diet can significantly help reduce symptoms. The following strategies can be very effective:

Prioritize bland foods: The BRAT diet (bananas, rice, applesauce, toast) is often recommended. Other gentle options include boiled eggs, saltine crackers, and porridge.
Stay hydrated: Drink plenty of fluids to prevent dehydration, which is a significant risk with persistent diarrhea. Water is best, but electrolyte-containing drinks can also be beneficial.
Avoid trigger foods: Steer clear of spicy, greasy, and fried foods, as these can irritate the digestive system. High-fiber foods like beans and certain vegetables should also be limited during an active episode.
Reduce dairy and caffeine: Some individuals find that milk, dairy products, coffee, and tea can exacerbate symptoms.

Over-the-Counter (OTC) Medications

For mild to moderate cases, OTC antidiarrheal medications like loperamide (Imodium) may be helpful. However, you must consult your doctor or pharmacist before taking any new medication, even OTC options, to ensure it is safe to use with Jakafi and your specific health conditions.

When to Contact Your Doctor

It is important to know when to seek medical advice for more severe or persistent symptoms. You should contact your healthcare provider immediately if you experience any of the following:

Diarrhea that lasts for more than two days
Fever alongside your diarrhea
Bloody stools or black, tarry stools
Signs of dehydration, such as extreme thirst, decreased urination, or dizziness
Severe stomach pain

Comparison of Gastrointestinal Side Effects in Clinical Trials

This table illustrates some reported gastrointestinal side effects of Jakafi based on clinical trial data and drug information sources. Note that prevalence can vary widely.


Side Effect	Myelofibrosis	Polycythemia Vera	Graft-Versus-Host Disease
Diarrhea	Reported incidence varies, with some trials showing ~12-13%.	Listed as a common side effect in some reports.	Often manageable, may require close monitoring.
Nausea	A less common non-hematologic side effect in some trials.	Reported in some patients, though often mild.	Can be a symptom, but incidence may vary.
Abdominal Pain	Reported, with prevalence varying between studies.	Listed as a possible, but not always common, side effect.	Can be a component of GVHD and side effect management.
Constipation	Not typically a major side effect, in contrast to some chemotherapies.	Can occur in some patients.	Not as frequently cited as diarrhea.

Communicating with Your Healthcare Team

Open communication with your healthcare provider is essential. Do not stop or change your Jakafi dose without first talking to them. Report any side effects, including diarrhea, so they can assess the situation and recommend appropriate management strategies, potentially including dose adjustment if necessary. The goal is to manage side effects while maintaining the therapeutic benefits of the medication.

Conclusion

While Jakafi (ruxolitinib) is an effective treatment for certain blood disorders, it can cause diarrhea as a documented and common side effect. The severity and frequency can differ, but the symptom is generally manageable with supportive care. By adhering to dietary guidelines, staying hydrated, and consulting with your healthcare provider before using any antidiarrheal medications, you can effectively minimize the impact of this side effect. Close monitoring and communication with your medical team are the most important steps to ensure a safe and successful treatment journey. For more information, read about other potential side effects based on information from Drugs.com or review the DailyMed label for Jakafi.

Frequently Asked Questions

For most patients, Jakafi-induced diarrhea is mild to moderate and manageable. However, if it becomes severe, persistent, or is accompanied by other symptoms like fever or bloody stools, it requires prompt medical attention to prevent complications like dehydration.

Focus on a bland diet, such as the BRAT diet (bananas, rice, applesauce, toast), and other easily digestible foods like boiled eggs, crackers, and soups. Avoid spicy, greasy, fried, and high-fiber foods, and consider limiting dairy and caffeine.

You should always consult your healthcare provider or pharmacist before taking any over-the-counter medications, including loperamide, while on Jakafi. They can determine if it's a safe and appropriate treatment option for you.

The duration can vary. In some clinical studies, the frequency of non-hematologic side effects like diarrhea decreased over time with longer-term Jakafi use. However, if your diarrhea persists for more than two days, you should contact your doctor.

Dose adjustment for Jakafi may be considered in cases of moderate to severe or persistent diarrhea. This decision should only be made by your healthcare provider after they have evaluated your condition.

No, you should never stop or change your Jakafi dose without first consulting your healthcare provider. Abruptly stopping treatment can have negative consequences. Your doctor will advise on the best course of action.

Look for signs such as extreme thirst, decreased urination, fatigue, dizziness, or confusion. Maintaining adequate hydration with water and electrolyte drinks is important to prevent this.