Side effects
The medicines
Osimertinib (Tagrisso): targeted therapy, tablets.Tap the side effect you have on the map to see how severe it is and what to do. Not everyone gets every side effect, and most are mild.
Loose stools (diarrhoea)
From: Osimertinib
1 loose stool more than usual
Manage at home
2 to 3 loose stools a day
Call or WhatsApp us today
4 or more loose stools, or blood, fever or dizziness
Go to emergency now
1 loose stool more than usual
Mild (grade 1)
1 loose stool more than usual in a day, otherwise well.
Manage at home. Drink plenty and eat soft food. Start loperamide if advised.
2 to 3 loose stools a day
Moderate (grade 2)
2 to 3 loose stools in a day, or tummy cramps.
Call or message the duty mobile today. We will tell you about loperamide and fluids. On immunotherapy, this needs a call today.
4 or more loose stools, or blood, fever or dizziness
Severe (grade 3 or 4)
4 or more loose stools in 24 hours , or any loose stools with blood, fever, or dizziness.
Go to the emergency department now. You may need fluids through a drip and tests. If you cannot reach KIMS quickly, go to the nearest hospital emergency.
What helps at home
Drink plenty: ORS, buttermilk, rice water, coconut water, clear soups. Eat soft, low-fibre food: curd rice, idli, khichdi, banana, toast. Avoid milk, oily and spicy food, raw salads and fruit juices until better. Keep the skin around the bottom clean and dry.
Medicines we use
Loperamide, as advised by your doctor. Do not take it if you have fever or blood in the stools, without asking us. On immunotherapy, loose stools may need steroids: always tell us.
Skin and nail changes
From: Acne-like rash: Osimertinib; Painful nail folds: Osimertinib; Dry, itchy skin: Osimertinib
Dry skin or mild rash
Manage at home
Painful peeling, or rash over a large area
Call or WhatsApp us today
Blisters, skin peeling off, or rash with fever
Go to emergency now
Dry skin or mild rash
Mild (grade 1)
Dry skin, mild rash or redness, without pain.
Manage at home. Moisturiser and sunscreen.
Painful peeling, or rash over a large area
Moderate (grade 2)
Painful redness or peeling of the hands or feet, or a rash over a large area, that affects daily work.
Call or message the duty mobile today. A cream, tablet or a short break in treatment can help.
Blisters, skin peeling off, or rash with fever
Severe (grade 3 or 4)
Blisters , skin peeling off, a rash with fever, a rash in the mouth or eyes, or a red, hot, swollen area with pus.
Go to the emergency department now. If you cannot reach KIMS quickly, go to the nearest hospital emergency.
What helps at home
Moisturise twice a day with a fragrance-free cream; urea cream for hands and feet. Use sunscreen and cover up in the sun. Bathe with lukewarm water and mild soap. Avoid tight shoes, hot water and long walks if hands and feet are sore. Keep nails short; wear gloves for housework.
Medicines we use
Antibiotic tablets and creams for EGFR rash; steroid creams; a short break or dose change for sore hands and feet.
Checked with tests
Uncommon but important. We look for these with blood tests, an ECG or scans.
Effect on the heart
From: Osimertinib
Some medicines can weaken the heart muscle or affect its rhythm.
When: Can happen during or after treatment.
What helps:
A heart scan (2D echo) or ECG is done before and during treatment. Most changes are found early on the echo and recover when the medicine is paused. Call or message the duty mobile if you have breathlessness on lying flat, swollen ankles, palpitations or chest pain.
Lung inflammation
From: Osimertinib
Rarely, some medicines inflame the lungs, causing dry cough or breathlessness.
When: Any time during treatment.
What helps:
Report any new cough or breathlessness early; it is treated with steroids. Scans and sometimes breathing tests are done. Call or message the duty mobile if you have new or worsening breathlessness, cough or fever.
Check your symptoms in My treatment
General information. Doses are not shown. Your own doctor may advise differently. When to seek help urgently
Written and medically reviewed by Dr Prathyusha Eaga, MD, DM (Medical Oncology). Last reviewed: 12 October 2026. Based on NCCN and ESMO guidelines.
Have questions?
Book a hospital visit, a video consultation or a second opinion.