What should I do if I forget to take Tukysa (tucatinib)?

If you forget to take Tukysa (tucatinib) or vomit after taking the medication, don’t take another dose of Tukysa (tucatinib) to try to make up for it. Just wait and take the medication at your next usually scheduled time. For example, if you typically take Tukysa (tucatinib) at 8:00 AM and 8:00 PM every day, and you forget to take the medication in the morning, skip the missed dose and wait to take your evening dose. Continue with how you usually take the medication the next day.

Is Tukysa (tucatinib) a kind of chemotherapy?

No. [Chemotherapy](https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/chemotherapy.html) is a term used for cancer medications that kill cancer cells in your body. Unlike traditional chemotherapy, Tukysa (tucatinib) slows cancer cell growth. As part of treatment, Tukysa (tucatinib) is taken together with a chemotherapy medication called [capecitabine (Xeloda)](https://www.goodrx.com/capecitabine/what-is).

Can Tukysa (tucatinib) treat any type of breast cancer?

No. Even though there are many [different types](https://www.goodrx.com/conditions/breast-cancer/breast-cancer-receptor-status-types) of breast cancer, Tukysa (tucatinib) treats advanced or metastatic [HER2-positive](https://www.goodrx.com/conditions/breast-cancer/her2-positive-breast-cancer) breast cancer. To figure out the [receptor type](https://www.goodrx.com/conditions/breast-cancer/breast-cancer-receptors) of your cancer, your provider will perform a [biopsy](https://www.cancer.org/cancer/breast-cancer/screening-tests-and-early-detection/breast-biopsy.html) or surgery to remove a small piece of your breast tissue. Knowing what type of receptor your cancer has will help your provider decide what treatment plans to consider and discuss with you. Tukysa (tucatinib) is specifically used for people who’ve already tried at least one other treatment plan that targets HER2, such as those with [Herceptin (trastuzumab)](https://www.goodrx.com/herceptin/what-is) or [Perjeta (pertuzumab)](https://www.goodrx.com/perjeta/what-is).

Tukysa

tucatinib

Used for Breast Cancer

Tukysa (tucatinib) is an oral medication that treats advanced or metastatic HER2-positive breast cancer. Tukysa (tucatinib) is used with other medications to treat your breast cancer. It’s a tablet that’s taken by mouth, but often causes diarrhea, which can be bothersome.

Reviewed by:

Lauren Morton, PharmD, BCPS

Cydnee Ng, PharmD

Last reviewed on December 20, 2022

What is Tukysa (tucatinib)?

What is Tukysa (tucatinib) used for?

Advanced HER2-positive breast cancer that can’t be surgically removed
Metastatic HER2-positive breast cancer that’s spread to other parts of the body

How Tukysa (tucatinib) works

Tukysa (tucatinib) is a tyrosine kinase inhibitor. It works by blocking the action of a protein called human epidermal growth factor receptor 2 (HER2). This protein is found on both normal and cancer cells. But in HER2-positive breast cancer, the cancer cells typically have more HER2 proteins than normal cells. When this protein is blocked by Tukysa (tucatinib), cancer cells can’t grow and spread as well.

Are you looking for information on Tikosyn (dofetilide) or Tykerb (lapatinib) instead?

Drug facts

Common Brands	Tukysa
Drug Class	Tyrosine kinase inhibitor
Controlled Substance Classification	Not a controlled medication
Generic Status	No lower-cost generic available
Availability	Prescription only

Common Brands

Tukysa

Drug Class

Tyrosine kinase inhibitor

Controlled Substance Classification

Not a controlled medication

Generic Status

No lower-cost generic available

Availability

Prescription only

Side effects of Tukysa (tucatinib)

The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.

Common Side Effects

When used with other anticancer medications:

Diarrhea (81%)
Rash, redness, pain, or blisters on the palms of your hands or soles of your feet (hand-foot syndrome, 63%)
Nausea (58%)
Liver damage (42%)
Vomiting (36%)
Pain, sores, blisters, or inflammation in the mouth (32%)
Lower appetite (25%)

Less Common Side Effects

Headache
Tiredness
Stomach pain
Joint pain
Nerve damage
Rash
Weight loss
Anemia
Nose bleed

Tukysa (tucatinib) serious side effects

Contact your healthcare provider immediately if you experience any of the following.

Severe diarrhea
Liver problems: yellowing of skin or whites of your eyes, dark-colored urine, right upper stomach pain or discomfort, itchy skin

Source: DailyMed

The following Tukysa (tucatinib) side effects have also been reported

Side effects that you should report to your care team as soon as possible:

Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
Liver injury—right upper belly pain, loss of appetite, nausea, light-colored stool, dark yellow or brown urine, yellowing skin or eyes, unusual weakness or fatigue

Side effects that usually do not require medical attention (report these to your care team if they continue or are bothersome):

Diarrhea
Fatigue
Nausea
Skin rash
Stomach pain
Vomiting

Pros and cons of Tukysa (tucatinib)

Pros

Can take with or without food
Available as a tablet so it’s more convenient than other treatment options that are injections
An option if your previous treatment didn’t work

Cons

Not used by itself to treat your breast cancer
Commonly causes diarrhea, which can be severe
Only available as a brand medication

Pharmacist tips for Tukysa (tucatinib)

Take Tukysa (tucatinib) with or without food at the same times each day (about 12 hours apart). Swallow the tablet whole so that the medication works properly. Don’t cut, chew, or crush the tablet, and don’t take any broken or cracked tablets.
If you have diarrhea from Tukysa (tucatinib), contact a provider right away. They might instruct you to take an antidiarrheal medication called loperamide (Imodium A-D) on an as-needed basis. Other things that can help include avoiding spicy and greasy foods and eating small meals with foods that are easier on the stomach.
Make sure to stay hydrated to avoid dehydration from possible diarrhea. During treatment, let your provider know if you have dry mouth, feel lightheaded or dizzy, or you’re not urinating as much, since these can be signs of dehydration.
Whether you’re female or male, if you or your partner can get pregnant, use birth control during treatment and for at least 1 week after your last dose. Let your provider know right away if you or your partner becomes pregnant. Tukysa (tucatinib) might cause harm to an unborn baby.
Tukysa (tucatinib) can also affect your ability to have children (fertility). If you have concerns about family planning, talk to your provider.
Certain medications, like gemfibrozil (Lopid) and itraconazole (Sporanox), can interact with Tukysa (tucatinib), so it’s important to tell your provider and pharmacist about all the medications you take or plan to take, including supplements and over-the-counter medications. Your provider can guide you to safer alternatives or recommend how to best take your medications.
Ask your healthcare provider or pharmacist about the best way to handle and dispose of Tukysa (tucatinib). Cancer medications can be very harmful to people who handle or come into contact with them, so you need to get rid of them safely.

Common questions about Tukysa

Your care team will talk with you about how long you’ll need to take Tukysa. In general, you’ll continue to take Tukysa as long as your cancer doesn’t get worse. But if your cancer progresses, if you experience certain side effects like diarrhea, or if your provider finds that the medication is causing liver damage, your care team will discuss with you about what this means and if you need to pause or stop treatment. Don’t stop taking Tukysa without talking with your healthcare provider first.

If you forget to take Tukysa or vomit after taking the medication, don’t take another dose of Tukysa to try to make up for it. Just wait and take the medication at your next usually scheduled time. For example, if you typically take Tukysa at 8:00 AM and 8:00 PM every day, and you forget to take the medication in the morning, skip the missed dose and wait to take your evening dose. Continue with how you usually take the medication the next day.

No. Chemotherapy is a term used for cancer medications that kill cancer cells in your body. Unlike traditional chemotherapy, Tukysa slows cancer cell growth. As part of treatment, Tukysa is taken together with a chemotherapy medication called capecitabine (Xeloda).

No. Even though there are many different types of breast cancer, Tukysa treats advanced or metastatic HER2-positive breast cancer. To figure out the receptor type of your cancer, your provider will perform a biopsy or surgery to remove a small piece of your breast tissue. Knowing what type of receptor your cancer has will help your provider decide what treatment plans to consider and discuss with you. Tukysa is specifically used for people who’ve already tried at least one other treatment plan that targets HER2, such as those with Herceptin (trastuzumab) or Perjeta (pertuzumab).

It isn’t recommended to breastfeed while receiving Tukysa. It’s not known if the medication can get into breast milk, but there’s a risk of serious harm to nursing infants if it does. Because of this risk, don’t breastfeed during Tukysa treatment and for 1 week after your last dose. Discuss with your provider if you have any questions about breastfeeding or other ways to feed your baby while taking Tukysa.

Risks and warnings for Tukysa (tucatinib)

Tukysa (tucatinib) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.

Diarrhea

Tukysa (tucatinib) can cause diarrhea. Though less common, severe cases can lead to complications like dehydration, low blood pressure, and even death. In studies, diarrhea typically happened within the first 2 weeks of starting Tukysa (tucatinib) and lasted about 8 days. If you begin to experience diarrhea or any changes in your bowel movements, let your provider know immediately. They can recommend you to take an antidiarrheal medication like loperamide (Imodium A-D). Your provider might also lower your dose, pause treatment until your diarrhea gets better, or in severe cases, have you stop taking Tukysa (tucatinib).

Liver problems

Tukysa (tucatinib) can sometimes cause severe liver damage. Because of this risk, your provider will check your liver health through lab work while you’re taking this medication. Let your provider know if you develop any symptoms of liver problems, such as itchy skin, yellowing of skin or whites of your eyes, dark-colored urine, and pain or discomfort in the right upper stomach area. Your provider might lower your dose, pause treatment temporarily, or have you stop taking Tukysa (tucatinib).

Harm to unborn baby

Tukysa (tucatinib) might cause harm to an unborn baby. If you're a female who can get pregnant and you’re taking Tukysa (tucatinib), your provider might check to make sure you’re not pregnant before you start treatment. You’ll also need to use birth control during treatment and for at least 1 week after your last dose. If you’re a male taking Tukysa (tucatinib) and your partner is able to become pregnant, you should use birth control during treatment and for at least 1 week after your last dose as well. Let your provider know right away if you or your partner becomes pregnant during this time.

Tukysa (tucatinib) dosage

Typical dosage for Tukysa (tucatinib)

The typical dose is 300 mg taken orally twice a day (about 12 hours apart).

Your dose might be different if you have severe liver problems or if you're also taking certain medications (see Pharmacist Tips for more information).