Answer
Oct 29, 2026 - 09:51 AM
The most common side effects of TUKYSA (tucatinib) include:
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Diarrhea
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Nausea and vomiting
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Fatigue or tiredness
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Decreased appetite
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Skin rash
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Hand-foot syndrome: Redness, swelling, pain, or blisters on the palms of the hands or soles of the feet
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Mouth sores (stomatitis)
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Liver problems: Including elevated liver enzymes
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Anemia: Low red blood cell counts
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Abdominal pain
The specific side effects depend on whether TUKYSA is used with trastuzumab and capecitabine, trastuzumab and pertuzumab, or trastuzumab alone. Muscle and joint pain, fever, and infusion-related reactions are also common with certain treatment combinations.
Serious side effects to watch for
TUKYSA can cause severe diarrhea, dehydration, and liver damage. Contact your healthcare provider promptly if you experience persistent or severe diarrhea, yellowing of the skin or eyes, dark urine, severe abdominal pain, or unusual fatigue.
Your healthcare provider may adjust the dosage, temporarily interrupt treatment, or discontinue TUKYSA if serious side effects occur. Do not change your dose without medical guidance.
