Why Understanding Yervoy Side Effects Is So Important

Yervoy (ipilimumab) is an immunotherapy drug that works by boosting your immune system to fight cancer. While this is a powerful approach, it comes with a trade-off: your revved-up immune system can sometimes attack healthy tissues too. These are called immune-mediated side effects, and they can be serious if not caught early.

This guide covers the most common side effects, the serious ones you need to watch for, and exactly when you should contact your doctor. If you're starting Yervoy treatment or considering it, this information could be life-saving.

For a general overview of the drug, see our guide on what Yervoy is and how it's used.

Common Side Effects of Yervoy

Most patients experience at least some side effects during treatment. The following are the most frequently reported:

• Fatigue — Feeling unusually tired is one of the most common complaints. It may start after your first infusion and can last throughout treatment.
• Diarrhea — Loose or watery stools are common. Mild diarrhea can often be managed at home, but severe diarrhea needs immediate medical attention.
• Itching (pruritus) — Many patients develop itchy skin, sometimes without a visible rash.
• Rash — Skin rashes can range from mild redness to more widespread breakouts.
• Nausea and vomiting — Some patients feel nauseated, especially around infusion days.
• Decreased appetite — You may not feel as hungry as usual.
• Abdominal pain — Mild stomach discomfort is common and may accompany diarrhea.
• Headache — Occasional headaches are reported during treatment.
• Fever — Low-grade fevers can occur as your immune system responds to treatment.
• Joint pain — Some patients notice aching in their joints.
• Constipation — Less common than diarrhea but still reported.

These side effects are often manageable with supportive care. Your oncology team will give you guidance on handling them at home.

Serious Immune-Mediated Side Effects

Yervoy carries a boxed warning — the most serious type of warning from the FDA — about immune-mediated adverse reactions. These happen when your immune system, supercharged by the drug, attacks your own healthy organs. They can occur during treatment or even weeks to months after your last dose.

Immune-Mediated Colitis

This is inflammation of the colon and one of the most common serious side effects. Symptoms include:

• Severe diarrhea (more than 6 stools per day above baseline)
• Blood or mucus in your stool
• Severe abdominal pain or cramping
• Fever with diarrhea

In rare cases, colitis can lead to intestinal perforation, which is a medical emergency.

Immune-Mediated Hepatitis

Yervoy can cause liver inflammation. You may not feel symptoms at first, which is why your doctor will check your liver enzymes with regular blood tests. Warning signs include:

• Yellowing of the skin or eyes (jaundice)
• Dark urine
• Severe nausea or vomiting
• Pain in the upper right side of your abdomen
• Easy bruising or bleeding

Immune-Mediated Skin Reactions

While mild rashes are common, Yervoy can rarely cause severe skin conditions including Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Seek emergency care if you notice:

• Blistering or peeling skin
• Painful sores in your mouth, throat, or eyes
• Widespread rash with fever

Immune-Mediated Endocrinopathies

Yervoy can affect your hormone-producing glands. The most common endocrine side effect is hypophysitis (inflammation of the pituitary gland). Symptoms may include:

• Persistent or unusual headaches
• Extreme fatigue beyond what's normal for treatment
• Dizziness or fainting
• Changes in mood or behavior
• Hair loss, feeling cold, or weight gain (signs of hypothyroidism)

Other Serious Immune-Mediated Reactions

Though less common, Yervoy can also trigger:

• Pneumonitis — Lung inflammation causing cough, chest pain, or shortness of breath.
• Nephritis — Kidney inflammation that may show up first in blood tests.
• Neuropathy — Nerve damage causing numbness, tingling, or weakness.
• Myocarditis — Heart inflammation, which can be fatal. Report chest pain, irregular heartbeat, or shortness of breath immediately.
• Uveitis — Eye inflammation causing pain, redness, or vision changes.

When to Call Your Doctor

Contact your oncology team right away if you experience any of the following:

• Diarrhea that is severe, bloody, or lasts more than 24 hours
• Yellowing of your skin or eyes
• Severe abdominal pain
• Shortness of breath or new cough
• Chest pain or irregular heartbeat
• Vision changes or eye pain
• New or worsening headaches
• Extreme fatigue, dizziness, or fainting
• Numbness, tingling, or muscle weakness
• Blistering or peeling skin
• Fever above 100.4°F (38°C)
• Any new symptom that feels severe or unusual

Do not wait to see if symptoms improve on their own. Early treatment of immune-mediated reactions — usually with high-dose corticosteroids — is critical. Delays can lead to permanent organ damage or death.

How Side Effects Are Managed

Your medical team will monitor you closely throughout Yervoy treatment. Here's what to expect:

• Regular blood tests — Before each infusion, you'll have blood drawn to check liver function, kidney function, thyroid levels, and other markers.
• Symptom check-ins — Your care team will ask about new symptoms at every visit.
• Corticosteroids — For moderate to severe immune-mediated reactions, high-dose steroids like prednisone are the standard treatment. These are typically started quickly and tapered gradually.
• Treatment delays or discontinuation — If side effects are severe, your doctor may delay your next infusion or stop Yervoy permanently. This is a safety measure, not a failure of treatment.
• Hormone replacement — If Yervoy damages your pituitary, thyroid, or adrenal glands, you may need hormone replacement therapy for the long term.

Side Effects When Yervoy Is Combined with Nivolumab

Yervoy is often used in combination with nivolumab (Opdivo) for cancers like melanoma, kidney cancer, and lung cancer. This combination is more effective for some cancers but also carries a higher risk of side effects. Up to 60% of patients on the combination may experience grade 3 or 4 (severe) adverse events, compared to about 25-30% on Yervoy alone.

If you're receiving the combination, it's even more important to report symptoms early. Learn more about Yervoy drug interactions and what to discuss with your doctor.

Tips for Managing Mild Side Effects at Home

• Stay hydrated. Drink plenty of water, especially if you have diarrhea.
• Eat bland foods. The BRAT diet (bananas, rice, applesauce, toast) can help with stomach upset.
• Use gentle skin care. Fragrance-free moisturizers and mild soaps can help with rash and itching.
• Rest when you need to. Fatigue is real. Don't push through it — let your body recover.
• Keep a symptom journal. Write down what you experience each day so you can share it with your care team at your next visit.
• Take your temperature daily. Catching a fever early can help your doctor respond faster.

The Bottom Line

Yervoy is a life-changing treatment for many cancer patients, but it requires careful monitoring. Know the warning signs, keep your medical team informed, and don't hesitate to call if something feels wrong. Early action makes all the difference.

For more about Yervoy, read our guides on how Yervoy works, finding a doctor who prescribes Yervoy, and saving money on Yervoy.