• Diarrhea. Diarrhea is a common side effect of NERLYNX, but it can also be severe. You may lose too much body salts and fluid, and get dehydrated. When you start NERLYNX, your healthcare provider should prescribe the medicine loperamide for you during your first 2 months (56 days) of NERLYNX and then as needed. Be sure that your healthcare provider prescribes anti-diarrheals with NERLYNX. Anti-diarrheals must be started with the first dose of NERLYNX. To help prevent or reduce diarrhea:
  • You should start taking loperamide with your first dose of NERLYNX.
  • Keep taking loperamide during the first 2 months (56 days) of NERLYNX treatment and then as needed. Your healthcare provider will tell you exactly how much and how often to take this medicine.
  • Your healthcare provider may also need to give you other medicines to manage diarrhea when you start treatment with NERLYNX. Follow your healthcare provider’s instructions on how to use these anti-diarrheal medicines.
  • Always take anti-diarrheals exactly as your healthcare provider tells you.
  • While taking anti-diarrheals, you and your healthcare provider should try to keep the number of bowel movements that you have at 1 or 2 bowel movements each day.
  • Tell your healthcare provider if you have more than 2 bowel movements in 1 day, or you have diarrhea that does not go away.
  • Call your healthcare provider right away, as instructed, if you have severe diarrhea or if you have diarrhea along with weakness, dizziness, or fever.
  • After 2 months (56 days) of treatment with NERLYNX, follow your healthcare provider’s instructions about taking loperamide as needed to control diarrhea.

Your healthcare provider may change your dose of NERLYNX, temporarily stop or completely stop NERLYNX if needed to manage your diarrhea.

See "What are the possible side effects of NERLYNX?" for more information about side effects.

What is NERLYNX?

• NERLYNX is a prescription medicine used alone to treat adults with early-stage human epidermal growth factor receptor 2 (HER2)-positive breast cancer and who have previously been treated with trastuzumab-based therapy.
• NERLYNX is also used with a medicine called capecitabine to treat adults with HER2-positive breast cancer that has spread to other parts of the body (metastatic) and who have received 2 or more anti-HER2 therapy medicines for metastatic breast cancer.

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

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

• have liver problems. You may need a lower dose of NERLYNX.
• are pregnant or plan to become pregnant. NERLYNX can harm your unborn baby. If you are a female who can become pregnant:
  • Your healthcare provider should do a pregnancy test before you start taking NERLYNX.
  • You should use effective birth control (contraception) during treatment and for at least 1 month after your last dose of NERLYNX.
  • Talk with your healthcare provider about forms of birth control that you can use during this time.
  • Tell your healthcare provider right away if you become pregnant during treatment with NERLYNX.
  • Males with female partners who can become pregnant should use effective birth control during treatment and for 3 months after your last dose of NERLYNX.

• are breastfeeding or plan to breastfeed. It is not known if NERLYNX passes into your breast milk. Do not breastfeed during treatment and for at least 1 month after your last dose of NERLYNX.

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. Especially tell your healthcare provider if you take medicines used to decrease stomach acid, called proton pump inhibitors or PPIs. You should avoid taking these medicines during treatment with NERLYNX.

What are the possible side effects of NERLYNX?

NERLYNX may cause serious side effects, including:
See "What is the most important information I should know about NERLYNX?"

• Liver problems. Changes in liver function tests are common with NERLYNX. Your healthcare provider should do blood tests before you begin treatment, monthly during the first 3 months, and then every 3 months as needed during treatment with NERLYNX. Your healthcare provider will stop your treatment with NERLYNX if your liver tests show severe problems. Call your healthcare provider right away if you get any of the following signs or symptoms of liver problems:
  • tiredness
  • nausea
  • vomiting
  • pain in the right upper stomach-area (abdomen)
  • fever
  • rash
  • itching
  • yellowing of your skin or whites of your eyes

The most common side effects of NERLYNX when used alone include:

• diarrhea
• nausea
• stomach-area (abdomen) pain
• tiredness
• vomiting
• rash
• dry or inflamed mouth, or mouth sores
• decreased appetite
• muscle spasms
• upset stomach
• nail problems including color change
• dry skin
• swelling of your stomach-area
• nosebleed
• weight loss
• urinary tract infection

The most common side effects of NERLYNX in combination with capecitabine include:

• diarrhea
• nausea
• vomiting
• decreased appetite
• constipation
• tiredness/weakness
• weight loss
• dizziness
• back pain
• joint pain
• urinary tract infection
• upper respiratory tract infection
• swelling of your stomach-area
• kidney problems
• muscle spasms

These are not all of the possible side effects of NERLYNX. For more information, ask your Healthcare Provider.

Tell your doctor if you have any side effects that bother you or that does not go away. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

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