This medication is used to treat lung cancer. Osimertinib belongs to a class of drugs known as kinase inhibitors. It works by slowing or stopping the growth of cancer cells. It binds to a certain protein (epidermal growth factor receptor-EGFR) in some tumors.

Read the Patient Information Leaflet if available from your pharmacist before you start taking osimertinib and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

Take this medication by mouth with or without food as directed by your doctor, usually once daily.

If you have trouble swallowing the tablet whole, place the tablet into a container with a small amount of non-carbonated water (2 ounces/60 milliliters). Stir well until the tablet breaks into small pieces. The tablet will not completely dissolve. Do not crush the tablet or heat the mixture. Drink all of the mixture right away. Add at least another half a glass of water (4 ounces/120 milliliters) to the container and drink all of the mixture to make sure you are getting all of the drug. Use only non-carbonated water for mixing, and do not prepare a supply in advance. The mixture may also be given through a tube into the stomach (nasogastric tube). If you are giving this medication through a nasogastric tube, ask your health care professional for detailed instructions on how to give it.

The dosage is based on your medical condition and response to treatment.

Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time each day.

Do not increase your dose or use this drug more often or for longer than prescribed. Your condition will not improve any faster, and your risk of serious side effects will increase.

Diarrhea, mouth sores, dry/itchy skin, tiredness, back pain, headache, or loss of appetite may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, such as:

• easy bruising/bleeding
• changes in your nails (such as nail tenderness/irritation/redness, change in nail color)
• signs of eye disease (such as vision changes, eye redness/pain, light sensitivity, eye discharge)
• signs of low level of sodium in the blood (such as nausea, extreme drowsiness, mental/mood changes, seizures)

Get medical help right away if you have any very serious side effects, such as:

• slow/fast/irregular heartbeat
• severe dizziness
• fainting
• slow/shallow breathing
• symptoms of heart failure (such as swelling ankles/feet, unusual tiredness, unusual/sudden weight gain)
• new or worsening symptoms of lung disease (such as shortness of breath, chest pain, cough, fever)
• signs of blood clots (such as pain/swelling/warmth in the groin/calf)

This medication may lower your ability to fight infections. This may make you more likely to get a serious (rarely fatal) infection or make any infection you have worse. Tell your doctor right away if you have any signs of infections (such as sore throat that doesn't go away, fever, chills).

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, such as:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

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.

Before taking osimertinib, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history.

Osimertinib may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away.

The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using osimertinib, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions:

• certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG)
• family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death)

Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/"water pills") or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using osimertinib safely.

This drug may cause blurred vision. Do not drive, use machinery, or do anything that needs clear vision until you are sure you can perform such activities safely. Limit alcoholic beverages.

Osimertinib can make you more likely to get infections or may make current infections worse. Stay away from anyone who has an infection that may easily spread (such as chickenpox, COVID-19, measles, flu). Talk to your doctor if you have been exposed to an infection or for more details.

Tell your health care professional that you are using osimertinib before having any immunizations/vaccinations. Avoid contact with people who have recently received live vaccines (such as flu vaccine inhaled through the nose).

To lower the chance of getting cut, bruised, or injured, use caution with sharp objects like razors and nail cutters, and avoid activities such as contact sports.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Older adults may be more sensitive to the side effects of this drug, especially QT prolongation (see above).

Tell your doctor if you are pregnant or plan to become pregnant. You should not become pregnant while using osimertinib. Osimertinib may harm an unborn baby. Your doctor should order a pregnancy test before you start this medication. Women using this medication should ask about reliable forms of birth control during treatment and for 6 weeks after the last dose. Men using this medication should ask about reliable forms of birth control during treatment and for 4 months after the last dose. If you or your partner becomes pregnant, talk to your doctor right away about the risks and benefits of this medication.

It is unknown if this drug passes into breast milk. Because of the possible risk to the infant, breastfeeding is not recommended while using this drug and for 2 weeks after the last dose. Consult your doctor before breastfeeding.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669.

Do not share this medication with others.

Lab and/or medical tests (such as heart imaging, complete blood count) should be done before you start taking this medication and while you are taking it. Keep all medical and lab appointments. Consult your doctor for more details.

If you miss a dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.