Common Side Effects of Tucatinib and Their Management

Release date: 2026-05-25 15:21:23     Recommended: 22

Common Side Effects of Tucatinib and Their Management

In clinical studies, nearly all patients experienced some side effects, but most were mild to moderate. When tucatinib is combined with trastuzumab and capecitabine, the most common side effects include: diarrhea; rash, redness, pain, swelling, or blisters on the palms of the hands or soles of the feet; nausea; elevated liver function test results; vomiting; mouth sores (stomatitis); decreased appetite; decreased red blood cell count (anemia); and rash. Diarrhea is the most common and can sometimes be severe, leading to dehydration, low blood pressure, kidney problems, or even death. Therefore, you should immediately inform your healthcare provider if you experience changes in bowel habits or severe diarrhea. Your doctor may prescribe anti-diarrheal medication and adjust the dose of tucatinib or temporarily stop treatment as needed.

Serious Side Effects of Tucatinib and Warning Signs to Watch For

Serious side effects occurred in 26% of patients receiving the tucatinib regimen, with the most common being diarrhea, vomiting, nausea, abdominal pain, and seizures. Additionally, tucatinib may cause severe liver problems. Your doctor will check your liver function with blood tests before starting treatment and every 3 weeks (or as needed) during treatment. You must seek immediate medical attention if you experience symptoms such as yellowing of the skin or eyes, dark (tea-colored) urine, pain in the upper right abdomen, unusual tiredness, loss of appetite, or bleeding or bruising more easily than usual. Also, tucatinib may reduce fertility in males and females; if you have concerns about fertility, discuss them with your doctor in advance. Hair loss was uncommon in both treatment arms of the study (4.7% in the tucatinib group vs. 3.6% in the control group).

Information You Must Tell Your Doctor Before Taking Tucatinib

Before taking tucatinib, be sure to tell your healthcare provider about all your health conditions, especially: whether you have liver disease; whether you are pregnant or plan to become pregnant (tucatinib may harm a fetus). Females of childbearing potential need a pregnancy test before starting treatment and should use effective contraception during treatment and for 1 week after the last dose. If you become pregnant or suspect you are pregnant during treatment, tell your doctor immediately. Male patients with female partners of childbearing potential should also use effective contraception during the same period. In addition, do not breastfeed during treatment and for 1 week after the last dose. Also, list all the medications you are taking (including prescription drugs, over-the-counter medicines, vitamins, and herbal supplements), because tucatinib may interact with other medications.