Osimertinib is used as the first treatment for a certain type of nonsmall-cell lung cancer (NSCLC) that has spread to other parts of the body. It is also used in people who could not be treated successfully with other similar chemotherapy medications. Osimertinib is in a class of medications called kinase inhibitors. It works by blocking the action of the abnormal protein that signals cancer cells to multiply. This helps stop or slow the spread of cancer cells and may help shrink tumors.

Side Effects Of Osimertinib

Osimertinib may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • diarrhea
  • constipation
  • rash
  • itching
  • dry or cracking skin
  • eczema
  • nausea
  • vomiting
  • loss of appetite
  • swelling or sores in the mouth
  • back pain
  • nail changes including swelling, redness, pain, splitting, breaking, and separation or loss from the nailbed.

Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately or get emergency medical treatment:

  • fast, or pounding heartbeat; shortness of breath, swelling of ankles or feet, feeling lightheaded
  • new or worsening shortness of breath, difficulty breathing, or cough; fever
  • chest pain
  • extreme tiredness
  • swollen, red, teary, or painful eyes; sensitivity to light; vision changes

Osimertinib may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

Warnings & Precautions

Before taking osimertinib:

  • tell your doctor and pharmacist if you are allergic to osimertinib, any other medications, or any of the ingredients in the osimertinib tablet. Ask your pharmacist for a list of the ingredients.
  • tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements you are taking or plan to take. Be sure to mention any of the following: anagrelide (Agrylin); arsenic trioxide (Trisenox); carbamazepine (Carbatrol, Epitol, Equetro, Tegretol, Teril); chloroquine (Aralen); chlorpromazine; cilostazol (Pletal); citalopram (Celexa); donepezil (Aricept); escitalopram (Lexapro); haloperidol (Haldol); heart or blood pressure medications; methadone (Dolophine, Methadose); oxaliplatin (Eloxatin); phenytoin (Dilantin, Phenytek); pimozide (Orap); quinidine (in Nuedexta); rifampin (Rifadin, Rimactane, in Rifamate, Rifater); rosuvastatin (Crestor); sulfasalazine (Azulfidine); thioridazine; topotecan (Hycamtin); and vandetanib (Caprelsa). Your doctor may need to change the doses of your medications or monitor you carefully for side effects. Many other medications may also interact with osimertinib, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list.
  • tell your doctor what herbal products you are taking, especially St. John’s wort. Your doctor will probably tell you not to take St. John’s wort while taking osimertinib.
  • tell your doctor if you have or have ever had long QT syndrome (a condition that increases the risk of developing an irregular heartbeat that may cause fainting or sudden death); an irregular heartbeat; heart failure (a condition in which the heart is unable to pump enough blood to the other parts of the body); higher or lower than normal levels of sodium, potassium, calcium, or magnesium in your blood; eye problems; or other lung conditions.
  • you should know that osimertinib may decrease fertility in men and women. However, you should not assume that you or your partner cannot become pregnant. Tell your doctor if you are pregnant, or plan to become pregnant. You should not become pregnant while you are taking osimertinib. Use effective birth control during your treatment with osimertinib, and for 6 weeks after your final dose. If you are a male and your partner can become pregnant, you should use effective birth control during your treatment and for 4 months after your final dose. Talk to your doctor about birth control methods that will work for you. If you or your partner become pregnant while taking osimertinib, call your doctor immediately. Osimertinib may harm the fetus.
  • tell your doctor if you are breastfeeding. Your doctor may tell you not to breastfeed during your treatment and for 2 weeks after your final dose.

Osimertinib Dosage

Osimertinib comes as a tablet to take by mouth. It is usually taken with or without food once a day. The length of your treatment depends on how well this medication works for you, and the side effects that you experience. Take osimertinib at around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take osimertinib exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

If you cannot swallow the tablets, place the tablet into 4 tablespoons (2 oz [60 mL]) of water and stir until the tablet is in small pieces. Drink the mixture right away. Pour in another half a cup (4 oz [120 mL]) to a cup of water (8 oz [240 mL]) to the container you used, rinse, and drink to make sure you get the full dose of osimertinib. Do not use carbonated water or any other liquid to dissolve the osimertinib tablet. Do not crush the tablet or heat the mixture. If you have a nasogastric (NG) tube, your doctor or pharmacist will explain how to give this mixture through an NG tube.

Your doctor may temporarily or permanently stop your treatment or decrease your dose of osimertinib depending on the side effects that you experience. Be sure to talk to your doctor about how you are feeling during your treatment. Do not stop taking osimertinib without talking to your doctor.

Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient.


Keep all appointments with your doctor and the laboratory. Your doctor will order certain heart function tests before and during your treatment to be sure it is safe for you to take osimertinib, and to check your body’s response to the medication.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.


All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.