Important Safety Information

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What are the possible side effects of TUKYSA?

TUKYSA may cause serious side effects, including:

  • Diarrhea (watery, loose, or frequent stools) is common and can sometimes be severe. Tell your healthcare provider if you have a change in your bowel movements or severe diarrhea. Severe diarrhea can cause a loss of too much body fluids (dehydration), low blood pressure, kidney problems, and death. Your healthcare provider may prescribe medicines to treat your diarrhea during treatment with TUKYSA.
  • Liver Problems, including severe cases. Your healthcare provider will test your blood to check your liver function before starting and every 3 weeks during treatment with TUKYSA, or as needed. Tell your healthcare provider right away if you have any signs and symptoms of liver problems including itching, yellowing of your skin or eyes, dark or brown urine (tea-colored), pain in the right upper stomach area (abdomen), feeling very tired, decreased appetite, or bleeding or bruising more easily than normal.

The most common side effects of TUKYSA in combination with trastuzumab in adults with RAS wild-type HER2-positive colorectal cancer include:

  • diarrhea
  • tiredness
  • rash
  • nausea
  • stomach-area (abdomen) pain
  • infusion-related reactions
  • fever

Your healthcare provider may change your dose of TUKYSA, temporarily stop, or permanently stop treatment with TUKYSA if you have certain side effects.

TUKYSA may cause fertility problems in males and females, which may affect the ability to have children. Talk to your healthcare provider if you have concerns about fertility.

These are not all the possible side effects of TUKYSA. Discuss side effects with your healthcare provider. You may report side effects to FDA at 1-800-FDA-1088 or

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What should I tell my healthcare provider before taking TUKYSA?

Before taking TUKYSA, tell your healthcare provider about all of your medical conditions, including if you:

  • have liver problems.
  • are pregnant or plan to become pregnant. TUKYSA can harm your unborn baby.

    Females who can become pregnant: Your healthcare provider will do a pregnancy test before you start taking TUKYSA. Use effective birth control (contraception) during TUKYSA treatment and for 1 week after the last dose of TUKYSA. Tell your healthcare provider right away if you become pregnant or think you may be pregnant during treatment with TUKYSA.

    Males with a female partner who can become pregnant:
    Use effective birth control during TUKYSA treatment and for 1 week after the last dose of TUKYSA.
  • are breastfeeding (nursing) or plan to breastfeed. Do not breastfeed during treatment with TUKYSA and for 1 week after the last dose of TUKYSA.

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. TUKYSA may affect the way your other medicines work, and other medicines may affect the way TUKYSA works. Keep a list of all the medicines you take and show it to your healthcare provider and pharmacist every time you get a new medicine.



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What is TUKYSA?

TUKYSA is a prescription medicine used with the medicine trastuzumab to treat adults with RAS wild-type human epidermal growth factor receptor-2 (HER2) positive colorectal cancer that has spread to other parts of the body (metastatic), or cannot be removed by surgery, and who have received treatment with fluoropyrimidine-, oxaliplatin-, and irinotecan-based chemotherapy and it did not work or is no longer working.

This use is approved based on a clinical study that measured how many patients had a tumor response and how long that response lasted. Studies are ongoing to confirm the benefit of TUKYSA for this use.

It is not known if TUKYSA is safe and effective in children.