Hematologist
CION Cancer Clinics
TKI side effects that persist long term | CION Cancer Clinics
Most TKI side effects are worst in the first months and then ease. A few can persist for years or appear later: tiredness, cramps, puffiness, loose motions, and changes in blood sugar, cholesterol, heart, blood vessels or lungs. Which ones you face depends on your TKI. This page explains what to watch for, what the checks mean and when a symptom needs emergency care. At CION Cancer Clinics, every leukaemia, MDS and MPN case is reviewed by our haematologist and discussed at a tumour board before a plan is agreed.
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Medically reviewed by Dr. Basudev PokhrelConsultant Haematologist · last reviewed September 2026, next review due September 2027
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On this page
- Which TKI side effects can last for years?
- What do the long-term side effects usually feel like?
- How do you and your team deal with a side effect?
- What do the monitoring tests on your report mean?
- What do people wrongly assume about TKI side effects?
- What can you do to lower the long-term risks?
- Common questions about long-term TKI side effects
The short answer
Which TKI side effects can last for years?
Most TKI side effects are strongest in the first months and then ease. A smaller group can persist or appear years later, such as tiredness, muscle cramps, puffiness, loose motions, changes in blood sugar or cholesterol, and effects on the heart, blood vessels or lungs.
Why it depends on which TKI you take
Imatinib, dasatinib, nilotinib, bosutinib, ponatinib and asciminib all block the same faulty BCR-ABL signal. Each also touches other pathways in the body in its own way. That is why two people with the same CML can have very different long-term effects. Your follow-up tests are chosen to match the TKI you take.
Why the effects can creep up
Some long-term effects cause no symptoms at first. Rising cholesterol, higher blood sugar, raised blood pressure or narrowing of blood vessels can build slowly over years. You will not feel them until they are well established, so the routine blood tests and blood pressure checks matter even when you feel fine.
What this page cannot tell you
It cannot tell you whether a symptom you have now is caused by your tablet. Many things cause tiredness or aches. Your haematologist can judge that against your TKI, your other conditions and your tests.
Never stop, skip or lower your TKI on your own because of a side effect. Tell your team; there is usually a safer option.
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Symptoms that cannot wait
Chest pain or pressure, sudden breathlessness, sudden weakness or numbness of the face, arm or leg, slurred speech, a cold or painful leg, or bleeding that will not stop need emergency care now. Call 108 or go to the nearest emergency department and say you take a TKI for CML. Do not wait for your next clinic visit.
Not sure whether this applies to you?
Ask an oncologistWhat people notice
What do the long-term side effects usually feel like?
These are the ones people describe most often after the first year. Not everyone gets them, and most are manageable.
Tiredness
A steady lack of energy rather than sleepiness. It can be made worse by a low haemoglobin, a slow thyroid or poor sleep, which your team can check for separately.
Muscle cramps and aches
Often in the hands, calves or feet, sometimes at night. Staying well hydrated and gentle stretching help some people. Tell your team if the cramps are severe, as blood salts may need checking.
Puffiness and fluid
Swelling around the eyes in the morning, or in the ankles. With some TKIs fluid can collect around the lungs, which causes breathlessness and needs to be reported the same week.
Gut and skin changes
Loose motions, indigestion, a rash, dry skin or lighter patches of skin and hair. These are usually mild but can wear you down over time.
Worth mentioning
- Loose motions that affect daily life
- A rash that spreads or blisters
What to do
How do you and your team deal with a side effect?
Write it down
Note when it started, how often it happens and what makes it better or worse. A short diary on your phone is far more useful to your doctor than a memory at the next visit.
Tell your team early
Report it at the next visit, or sooner if it affects work, sleep or eating. Early effects are usually easier to settle.
Check for other causes
Your haematologist may test your thyroid, salts, liver, kidneys, sugar or heart before blaming the tablet.
Adjust the plan together
Options include supportive medicines, a pause, a dose change or a different TKI. Only your haematologist decides this, based on your response.
On your report
What do the monitoring tests on your report mean?
- Lipid profile
- Cholesterol and fats in the blood. Some TKIs can raise them over time.
- HbA1c
- Your average blood sugar over recent months. Checked because some TKIs affect sugar control.
- ECG
- A tracing of the heart's rhythm. Some TKIs can change it, so it may be done before and during treatment.
- Echocardiogram
- An ultrasound of the heart, used to look at its pumping and the pressure in the lungs.
- Pleural effusion
- Fluid collecting around the lungs. It is linked mainly with dasatinib.
- LFT and KFT
- Liver and kidney function tests, repeated to catch strain on these organs early.
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Commonly believed
What do people wrongly assume about TKI side effects?
"If I have side effects, the tablet is too strong and I should take less."
Side effects do not tell you how well the tablet is working against CML. Lowering it yourself can let the BCR-ABL level rise. Any change is made by your haematologist, who can weigh the side effect against your latest result.
"Feeling nothing from the tablet means it is not working."
Many people have very few side effects and an excellent response. The BCR-ABL test, not how you feel, shows whether the treatment is working.
"Once the first year passes, nothing new can happen."
Most effects settle early, but heart, blood vessel, sugar and lung effects can appear later. That is why routine checks continue for as long as you take a TKI.
"Changing TKI means the CML has become worse."
A switch is often made purely because of side effects, while the CML is well controlled. It is a common and planned step, not a sign of failure.
Looking after yourself
What can you do to lower the long-term risks?
You cannot control every side effect, but you can reduce the risks that build slowly. The biggest gains come from the same habits that protect anyone's heart and blood vessels.
Heart and blood vessels
Stop smoking and chewing tobacco. Keep blood pressure, sugar and cholesterol checked and treated. Walk most days if you are able. These matter more on nilotinib and ponatinib, which carry a higher risk of narrowed arteries.
Other medicines and doctors
If a cardiologist, diabetologist or general physician starts a new medicine, make sure they know about your TKI. Some heart and cholesterol medicines interact with TKIs, so the prescriptions need to be coordinated.
Who needs closer checks
People who already have diabetes, heart disease, high blood pressure, a past stroke or lung disease usually need closer monitoring from the start. Some TKIs are less suitable for them, which your haematologist considers when choosing or changing the tablet.
Questions we are asked
Common questions about long-term TKI side effects
Do TKI side effects go away with time?
Many do. Tiredness, nausea, cramps and rashes often ease over the first months as your body adjusts. Some, such as puffiness or loose motions, can linger at a lower level. A few effects on the heart, blood vessels or lungs can appear later, which is why checks continue.
Can a TKI damage the heart?
Some TKIs can affect the heart rhythm or raise the risk of narrowed arteries, and one can raise the pressure in the lungs. The risk differs between tablets and between people. Your team may do an ECG, blood pressure checks and cholesterol tests to catch changes early. Report chest pain or breathlessness straight away.
Why am I breathless on dasatinib?
Dasatinib can cause fluid to collect around the lungs, which makes breathing harder, especially on exertion or lying flat. It can also cause cough or chest discomfort. Tell your team within days, and seek emergency care if breathlessness is sudden or severe. A chest X-ray usually shows whether fluid is present.
Can a TKI cause diabetes?
Nilotinib in particular can raise blood sugar, and some other TKIs can affect it too. Your team may check your sugar and HbA1c before and during treatment. If you already have diabetes, your diabetes doctor should know which TKI you take, as your sugar medicines may need adjusting.
Is weight gain or puffiness normal on imatinib?
Fluid retention is one of the most common effects of imatinib. It shows as puffy eyes, especially in the morning, or swollen ankles, and can add some weight. Reducing salt may help. Tell your team if the swelling is rapid, painful or comes with breathlessness, as that needs checking sooner.
Will I need to switch to another TKI?
Only if your haematologist feels the side effects or the response make a change worthwhile. Many people stay on their first TKI for years. When a switch happens because of side effects, the new TKI usually has a different pattern of effects, and your monitoring is adjusted to match it.
Do TKIs affect the thyroid or bones?
Some TKIs can slow the thyroid, which may add to tiredness and weight gain. Changes in bone and mineral balance have also been reported. These are checked with simple blood tests when there is a reason. Mention symptoms such as feeling cold, a slow pulse or new bone pain.
Can supplements help with side effects?
Some supplements and herbal products interact with TKIs and change how much of the tablet reaches your blood. Do not start any supplement, including calcium, magnesium or herbal remedies, without checking with your haematologist. They can suggest safe ways to ease cramps, loose motions or skin problems.
Your Haematologist
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Dr. Basudev Pokhrel reviews blood counts, transfusion needs and blood disorders, and works with the CION tumour board on blood cancers.
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Sources
- Cancer Research UK — Treatment for chronic myeloid leukaemia (CML)
- American Cancer Society — Targeted Therapy for Chronic Myeloid Leukemia
- Macmillan Cancer Support — Chronic myeloid leukaemia (CML)
- National Cancer Institute — Chronic Myelogenous Leukemia Treatment (PDQ) - Patient Version
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Switching TKI: Reasons and What ChangesWhen a side effect leads to a change of tabletFirst, Second and Third Generation TKIs ComparedHow the tablets differ from each otherLiving on a TKI for Decades: PracticalitiesDaily life on long-term treatmentChronic Myeloid Leukaemia (CML)The overview of CML and its treatment
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