Treatment and the treatment process

Side effects

For many people, side effects are the most frightening part of leukemia treatment. But side effects are not the same for everyone, most are temporary, and many can be prevented or eased. This topic describes the most common side effects, why they happen, what helps and which signs mean you should contact a doctor straight away.

Last updated: 30 September 2026~5 min read

Several dividing cells on a dark navy background: some are violet leukemia cells and others are soft pink healthy cells, and the same golden light falls on all of them. — **Figure 1.**Concept: medicines also touch healthy fast-dividing cells.

01Short answer

Side effects are problems caused by the effect of treatment on healthy cells and organs. In leukemia, the most common are low blood counts (infection, anemia, bleeding), nausea, mouth sores, hair loss, tiredness, diarrhea or constipation, nerve problems and effects on fertility. Their type and severity depend on the medicines, the dose and the person. Most go away after treatment ends, but some can appear years later, which is why regular follow-up matters even after treatment. Tell your team about every new symptom.

02Simple explanation

Leukemia medicines act on rapidly dividing cells. Healthy fast-dividing cells, such as the bone marrow, the lining of the mouth and gut, and hair roots, are affected too. Most side effects come from this.

Side effects are different for everyone. Of two people on the same treatment, one may notice very little and the other much more. Someone else’s experience may not reflect your own path.

Many side effects can be prevented: anti-sickness medicines, mouth care, infection prevention. So do not hide a problem; the earlier you mention it, the easier it is to help.

Some signs are urgent: fever, chills, shortness of breath, chest pain, bleeding that will not stop, confusion or being unable to drink. In these cases, do not wait; contact your team or emergency services straight away.

Even after treatment ends, some effects, for example on the heart, fertility or growth in children, can appear years later. These are called late effects, and there is a long-term follow-up plan for them.

03Scientific explanation

General principles: according to NCI, side effects happen when treatment affects healthy tissues and organs; they depend on the type of treatment, the dose and the person’s general health, and most go away after treatment ends. According to the American Cancer Society, the most common chemotherapy side effects are tiredness, hair loss, easy bruising and bleeding, infection, anemia, nausea and vomiting, appetite changes, mouth and throat sores, diarrhea or constipation, and nerve problems.

Nausea, mouth, hair: according to the 2020 ASCO guidelines, the choice of medicines to prevent nausea is based on how likely the chemotherapy is to cause it, and they are given in advance. NCI recommends regular, gentle mouth care to help prevent mouth sores. According to NCI, hair loss is usually temporary, and hair grows back after treatment ends, sometimes with a different colour or texture.

Medicine-specific effects: according to NCI, some medicines, such as vincristine, affect the peripheral nerves and cause numbness, tingling and pain in the hands and feet, as well as constipation. The effect of anthracyclines on the heart is monitored, and corticosteroids can change mood, sleep, appetite and blood sugar. NCI also describes memory and concentration problems, often called “chemo brain”.

Fertility and late effects: according to NCI, some treatments can affect fertility in women and men, so ways of preserving it should be discussed before treatment. According to the American Cancer Society and NCI, late effects can include heart problems, second cancers, hormone and growth problems, and bone and learning problems. The Children’s Oncology Group develops long-term follow-up guidance for people treated for cancer in childhood.

04What happens in the body?

Tiredness

Tiredness is the most common side effect, and it may not go away fully with rest. Anemia, poor sleep, stress and diet can make it worse. Short rests during the day, light physical activity when possible (such as walking) and sharing tasks all help. If you have sudden, severe weakness, shortness of breath or a racing heart, tell your team.

Hair loss

Some leukemia medicines cause hair loss, usually a few weeks after treatment starts. Short hair, a soft head covering and sun protection can help. Hair usually grows back after treatment ends. This change can be emotionally hard, and it is normal to talk about it.

Fine glowing strands of hair slowly growing upwards from a translucent layer of skin on a dark navy background, in warm, hopeful light. — **Figure 2.**Hair loss is usually temporary, and hair grows back.

Mouth and digestion

Mouth sores, taste changes, diarrhea or constipation are common. A soft toothbrush, alcohol-free mouthwashes, soft and mild foods and plenty of fluids help. If severe pain stops you eating, diarrhea happens several times a day or constipation lasts several days, tell your team; there are medicines for these.

A calm glowing road stretching towards the horizon on a dark navy background, with small points of light placed at even intervals along it. — **Figure 3.**Long-term follow-up continues after treatment.

Nerves, mood and thinking

If you notice numbness or tingling in your hands and feet, difficulty doing up buttons or a change in how you walk, tell your doctor; sometimes the dose or schedule of a medicine is changed. Concentration and memory problems, anxiety and sadness are also common. Psychological support, good sleep habits and daily plans can help.

After treatment

Regular check-ups continue after treatment ends, both to make sure the leukemia has not come back and to spot late effects in time. Keep a summary of the medicines and treatments you received and show it to any doctor in the future. In children, growth, learning and hormonal development are watched especially closely.

05How do side effects arise?

Four steps from the medicine to a side effect and help for it.

1MedicineActs on rapidly dividing cells.

2Healthy cellsBone marrow, linings and hair roots are affected too.

3SymptomsInfection, tiredness, mouth sores, hair loss.

4HelpPrevention, medicines and reporting in time.

InfectionA fever during neutropenia is urgent.

PreventionMany side effects can be prevented.

Mostly temporaryThey pass after treatment ends.

06Common side effects (simplified)

Side effect	What helps	Seek help straight away if
Infection risk	Hand hygiene, food safety, preventive medicines	Fever, chills, suddenly feeling unwell
Bleeding, bruising	Soft toothbrush, avoiding injury, platelet transfusions	Bleeding that will not stop, blood in vomit or stool, severe headache
Nausea, vomiting	Antiemetics in advance, small portions	Cannot keep fluids down, signs of dehydration
Mouth sores	Regular gentle mouth care, alcohol-free mouthwash	Pain that stops you eating or drinking
Tiredness	Short rests, light activity	Shortness of breath, chest pain, fainting
Nerve problems	Early reporting, care when walking	Sudden difficulty walking or using your hands
Hair loss	Soft head covering, sun protection	Usually not urgent; ask for emotional support

* Ask your team for written information about which side effects to expect and which signs mean you should call. How side effects are managed is decided only by your hematology team.

07Key terms

Side effect: A problem caused by the effect of treatment on healthy cells and organs.
Neutropenia: A low level of neutrophils, the cells that fight infection.
Mucositis: Inflammation and sores of the lining of the mouth and gut.
Alopecia: Hair loss.
Peripheral neuropathy: Numbness, tingling and pain in the hands and feet.
Antiemetic: A medicine against nausea and vomiting.
Chemo brain: Memory and concentration problems during and after treatment.
Fertility: The ability to have children.
Late effect: A problem that appears months or years after treatment.
Long-term follow-up: A plan of regular check-ups after treatment.

08Key points

Side effects come from damage to healthy fast-dividing cells.
They differ from person to person.
Most are temporary.
Many can be prevented or eased.
Fever and chills are urgent signs.
Do not hide new symptoms; report them early.
Discuss fertility before treatment starts.
Long-term follow-up is needed even after treatment.

09Frequently asked questions

If I have no side effects, does that mean treatment is not working?

No. Whether side effects happen, or how strong they are, does not show how well treatment is working. The response is judged only by blood and bone marrow tests.

Can treatment be stopped because of side effects?

Sometimes the team may change the dose, pause treatment or switch a medicine. But only the doctor decides this; do not stop a medicine or change the dose yourself.

What if the anti-sickness medicines do not help?

Tell your team. There are many medicines that work in different ways, and they can be combined. You do not have to put up with nausea.

Can folk remedies or supplements reduce side effects?

Some herbal products and supplements can interact with leukemia medicines, raise the risk of bleeding or harm the liver. Check with your hematologist before starting anything.

When can I go back to work or school?

It depends on the stage of treatment, your blood counts and how you feel. Some people return part-time during gentler phases. Talk this over with your team.

Will I definitely have late effects?

No. Not everyone has late effects, and the risk depends on the treatment received. Regular follow-up helps find and treat them early.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

Which side effects are most likely with my treatment?
Which medicines are available for nausea, pain or diarrhoea?
Which side effects are urgent and need an immediate call?
Should I keep a side-effect diary?

My questions

12Sources

National Cancer Institute (NCI). Side Effects of Cancer Treatment
National Cancer Institute (NCI). Nausea and Vomiting and Cancer Treatment
National Cancer Institute (NCI). Hair Loss (Alopecia) and Cancer Treatment
National Cancer Institute (NCI). Mouth and Throat Problems and Cancer Treatment
National Cancer Institute (NCI). Fatigue and Cancer Treatment
National Cancer Institute (NCI). Nerve Problems (Peripheral Neuropathy) and Cancer Treatment
National Cancer Institute (NCI). Memory or Concentration Problems and Cancer Treatment
National Cancer Institute (NCI). Diarrhea and Cancer Treatment
National Cancer Institute (NCI). Female Fertility and Cancer Treatment
National Cancer Institute (NCI). Male Fertility and Cancer Treatment
National Cancer Institute (NCI). Late Effects of Cancer Treatment
American Cancer Society. Chemotherapy Side Effects
American Cancer Society. Long-term and Late Effects of Cancer
Children’s Oncology Group. Survivorship
Journal of Clinical Oncology, 2020. Antiemetics: ASCO Guideline Update

Medical disclaimerThis information is for educational purposes only and does not replace medical advice.

Last updated: 30 September 2026← Back to the list

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