Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Abnormal heart rhythms: This medication can cause abnormal heart rhythms. Certain medications (e.g., sotalol, quinidine, thioridazine, chlorpromazine, droperidol, pimozide, moxifloxacin, mefloquine, pentamidine, arsenic trioxide, probucol, tacrolimus) can increase the risk of a type of abnormal heart rhythm called QT prolongation, and should not be used in combination with osimertinib. You are more at risk for this type of abnormal heart rhythm and its complications if you:
- are female
- are older than 65 years of age
- have a family history of sudden cardiac death
- have a history of heart disease or abnormal heart rhythms
- have a slow heart rate
- have congenital prolongation of the QT interval
- have diabetes
- have had a stroke
- have low potassium, magnesium, or calcium levels
- have nutritional deficiencies
If you have heart disease and abnormal heart rhythms, or are taking certain medications (e.g., verapamil, atazanavir), discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Birth control: If you or your partner is of childbearing age, talk to your doctor about appropriate birth control while using this medication. Birth control pills may become less effective when taken during treatment with osimertinib. Men who are taking this medication should not father a child while taking this medication and for at least 4 months after completing treatment with osimertinib.
Heart problems: This medication may cause or worsen symptoms of heart disease. If you have heart disease such as congestive heart failure, or arrhythmia, discuss with your doctor how this medication may affect the medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Contact your doctor as soon as possible if you develop symptoms of heart problems such as shortness of breath, chest pain, rapid heartbeat, or swollen ankles.
Liver function: Osimertinib is broken down by the liver. Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking this medication.
Lung inflammation: Lung inflammation (interstitial lung disease), causing difficulty breathing has occurred rarely in some people taking this medication. This complication can be serious and sometimes fatal. If you experience new or worsening shortness of breath or cough (with or without fever) at any time while you are taking osimertinib, contact your doctor immediately.
Pregnancy: Osimertinib may harm an unborn child if the mother takes it during pregnancy. This medication should not be used during pregnancy unless the benefits outweigh the risks. Women who may become pregnant must use an effective birth control method while taking this medication and for at least 2 months after taking the last dose of medication. If you become pregnant while taking this medication, contact your doctor immediately.
Breast-feeding: It is not known if osimertinib passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.
Children: The safety and effectiveness of using this medication have not been established for children and adolescents younger than 18 years of age.