Tucatinib (Tukysa®)

Author: Marisa Healy, BSN, RN
Last Reviewed: April 23, 2026

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Pronounce: too-KA-ti-nib

Classification: Kinase inhibitor

About Tucatinib (Tukysa®)

A kinase is an enzyme that helps a cell grow. There are different types of kinases. Each type affects a different phase of cell growth. Kinase inhibitors slow down the growth of cancer cells. 

How to Take Tucatinib

This medication comes in tablet form to be taken by mouth. It can be taken with or without food. It should be swallowed whole. It should not be broken, crushed, or chewed. It is taken twice daily, 12 hours apart. It is given in combination with other medications. If you miss a dose, skip that dose and continue to take your medication as scheduled.

It is important to make sure you are taking the correct amount of medication every time. Before every dose, check that what you are taking matches what you have been prescribed.

The blood levels of this medication can be affected by certain foods and medications, so they should be avoided. These include grapefruit, grapefruit juice, carbamazepine, phenobarbital, phenytoin, rifampin, St. John’s wort, gemfibrozil, digoxin, buspirone, darunavir, sirolimus, tacrolimus, triazolam, among others. Be sure to tell your healthcare provider about all medications and supplements you take.

Storage and Handling

Store your medication in the original container with the label. If you want to use a pillbox, talk to your pharmacist. Keep it in a dry place at room temperature unless your provider or pharmacist tells you otherwise. Keep containers out of reach of children and pets.

If a caregiver prepares your dose for you, they should consider wearing gloves or pour the pills directly from their container into the cap, a small cup, or directly into your hand. They should avoid touching the pills. They should always wash their hands before and after giving you the medication. Pregnant or nursing people should not prepare the dose for you. Ask your provider where to return any unused medication for disposal. Do not flush down the toilet or throw in the trash. 

Where Do I Get This Medication?

Some cancer medications are only available through specialty pharmacies. Your provider or pharmacist will start this process. Your insurance plan may also affect where you can get your medication.  Call your prescription plan provider to find out which specialty pharmacies are in-network.

Insurance Information

This medication may be covered by your prescription plan. If you qualify, you may be able to get financial help through patient assistance programs (PAP). Co-pay cards may also be available to lower your out-of-pocket cost if you have commercial (not Medicare/Medicaid/Tricare) insurance. Your pharmacist, social worker, or navigator can help find resources for financial support.

Possible Side Effects

These are some of the most common or most serious side effects of this medication. Talk with your provider about the side effects you are having and how they can be managed.

Diarrhea

Diarrhea is when you pass three or more stools in a day. Your providers can suggest medications to relieve diarrhea. Do not take any medications to manage your diarrhea without talking to your provider first, as your stool may need to be tested. To manage it, try eating foods that are low in fiber and bland, like white rice and boiled or baked chicken. Try not to eat raw fruits, vegetables, whole grain breads, cereals, and seeds. Soluble fiber is a type of fiber found in some foods that helps absorb (soak up) fluid. Foods high in soluble fiber are applesauce, bananas (ripe), canned fruit, oranges, boiled potatoes, white rice, foods made with white flour, oatmeal, cream of rice, cream of wheat, and farina. Stay hydrated by drinking 8 to 10 glasses of non-alcoholic, non-caffeinated fluid each day.

Hand-Foot Syndrome

Hand-foot syndrome (HFS) is a skin reaction on the palms of your hands and/or the soles of your feet. HFS can be caused by certain chemotherapy agents being absorbed (taken in) by your skin cells. HFS can start as a mild tingling, numbness, pins-and-needles feeling, redness, or pain or swelling of your hands and/or feet. It can lead to painful swelling, blistering, or peeling skin, making it hard to do your normal activities. Tell your providers right away if you have these symptoms, as they may need to change your chemotherapy dose or take a break to let your skin heal. Some ways to help prevent HFS are:

  • Keep your hands and feet clean and dry.
  • Avoid tight shoes or socks.
  • Avoid activities that put pressure on your palms or soles during treatment and for 1 week after treatment.
  • Use an alcohol-free moisturizer often, and do not use products with perfumes or scents.
  • Do not use very hot water for baths and showers

Nausea and/or Vomiting

Talk to your providers if you have nausea and/or vomiting. They can prescribe medications to help you. Making changes to your diet can also help. Avoid things that make your symptoms worse, like heavy or greasy/fatty foods and spicy or acidic foods, like tomatoes, lemons, and oranges. Try saltines or ginger ale to help your symptoms.  

Call your providers if you cannot keep fluids down for more than 12 hours or if you feel lightheaded or dizzy.

Fatigue

Fatigue can cause exhaustion, feeling worn out and that your body is "heavy" and hard to move, or being unable to focus. It is common when you have cancer, and it is not the same as feeling tired. You may need to adjust your schedule to manage fatigue. Plan times to rest during the day and save your energy for more important activities. Exercise can help lessen fatigue. Talk to your providers about ways to deal with this side effect.

Liver Toxicity

This medication can cause liver toxicity, or liver problems, which your provider may monitor for with blood tests called liver function tests. Symptoms may be:

  • Yellowing of your skin or eyes.
  • Dark or brown urine.
  • Pain in your abdomen (belly).

Tell your provider if you have any of these symptoms.

Mouth Ulcers (Mucositis)

This medication can cause sores or soreness in your mouth and/or throat, called mucositis. Tell your providers if your mouth, tongue, inside of your cheek, or throat becomes white, has ulcers, or is painful. Medications can be used to manage pain. Regular mouth care can help prevent or manage mouth sores. Some things you can do are:

  • Brush with a soft-bristle toothbrush or cotton swab twice a day.
  • Avoid mouthwashes that contain alcohol. A baking soda and/or salt with warm water mouth rinse (2 level teaspoons of baking soda or 1 level teaspoon of salt in an eight-ounce glass of warm water) can be used a few times each day.
  • If your mouth gets dry, eat moist foods, drink plenty of fluids (6 to 8 glasses), and suck on sugarless hard candy.
  • Avoid smoking and chewing tobacco, and drinking alcoholic beverages and citrus juices.

Muscle or Joint Pain/Aches and Headache

You may have joint or muscle pain/aches and headaches while taking this medication. Your provider can recommend medications and other ways to help relieve your pain.

Decrease in Appetite or Taste Changes

Nutrition is an important part of your care. Cancer treatment can affect your appetite and make it hard to eat. Ask your provider about nutrition counseling services. Some tips you can follow are:

  • Try to eat five or six small meals or snacks during the day, instead of 3 larger meals.
  • Nutritional supplements may help if you are not eating enough.
  • You may have a metallic taste or find that food has no taste. You may dislike foods or beverages that you liked before cancer treatment. These symptoms can last for months or longer after treatment ends.
  • Avoid any food that you think smells or tastes bad. If red meat is a problem, eat chicken, turkey, eggs, dairy products, and fish without a strong smell. Sometimes cold food has less of an odor.
  • Add extra flavor to meat or fish by marinating it in sweet juices, sweet and sour sauce, or dressing.
  • Use seasonings like basil, oregano, or rosemary to add flavor.

Electrolyte Abnormalities

This medication can affect your electrolytes (potassium, magnesium, sodium, calcium, etc.). Your electrolyte levels will be checked with blood tests. If your levels get too low, you may be given electrolytes by IV (intravenously through your vein) or by mouth. Talk to your provider before taking any supplements. 

Low Red Blood Cell Count (Anemia)

Anemia is when your red blood cell count is lower than normal. Red blood cells carry oxygen to the tissues in your body. When your red cell count is low, you may feel tired or weak. Tell your providers if you have shortness of breath, trouble breathing, or pain in your chest. If your count gets too low, you may receive a blood transfusion.

Secondary Cancers

A secondary cancer happens as a result of cancer treatment for another cancer. This is rare, but you should know your risk. Secondary cancers can be related to chemotherapy and other anti-cancer medications. Often, a secondary cancer is a blood cancer. This can happen years after treatment and is often related to repeated treatments or high doses. Your provider will watch your labs closely. They may suggest you have a blood test called a complete blood count with differential. This is often done each year if you had high risk therapies.

Reproductive Concerns

There is a higher risk of health problems for your baby if you are pregnant, become pregnant, or get someone pregnant while on this medication. To lower the risk of birth defects, you should use birth control (contraception) to avoid pregnancy. Talk with your provider about what kind of birth control is safest for you and your partner.

If you can become pregnant, you will need to use non-hormonal birth control during treatment and for 1 week after the last dose of this medication, even if your menstrual cycle has stopped or changed.

If you can get someone pregnant, you will need to use effective birth control during treatment and for 1 week after the last dose of this medication, even if you believe you are not producing sperm.

You should not breastfeed during treatment and for 1 week after the last dose of this medication.