Nausea, vomiting, mouth sores/pain, stomach/abdominal pain, loss of appetite, weight loss, tiredness, dry skin, nail changes, or muscle spasms may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.
People using this medication may have serious side effects. However, your doctor has prescribed this drug because he or she has judged that the benefit to you is greater than the risk of side effects. Careful monitoring by your doctor may decrease your risk.
Diarrhea is a common side effect. Drink plenty of fluids as directed by your doctor to lower your risk of dehydration. Your doctor should prescribe anti-diarrhea medication (such as loperamide) to help control your symptoms. Tell your doctor right away if you develop diarrhea that is severe or doesn't stop, or signs of dehydration (such as unusual decreased urination, unusual dry mouth/thirst, fast heartbeat, dizziness/lightheadedness). Your doctor may prescribe additional anti-diarrhea medications or temporarily stop/adjust your dose of neratinib.
Tell your doctor right away if you have any serious side effects, including: severe stomach/abdominal pain, yellowing eyes/skin, dark urine, signs of kidney problems (such as change in the amount of urine).
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
Neratinib can commonly cause a mild rash that is usually not serious. However, you may not be able to tell it apart from a rare rash that could be a sign of a severe allergic reaction. Get medical help right away if you develop any rash.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US -
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.