Chemotherapy-Induced Disorders (Chemotherapy Side Effects)

Why chemotherapy causes side effects

Chemotherapy drugs kill cells that divide rapidly. Cancer cells divide quickly, but so do:

• Bone marrow cells, which make blood cells
• Cells lining the mouth, stomach and intestines
• Hair follicles
• Cells in the ovaries and testes

Different drugs have different side effects, and the same drug affects people differently. Your care team will tell you what to expect from your specific regimen.

Common side effects

Low blood counts (myelosuppression)

Blood counts usually fall to their lowest point (the nadir) 7 to 14 days after each treatment and recover before the next cycle.

Neutropenic fever

A fever during neutropenia can be the only sign of a life-threatening infection, because the body cannot mount a normal response. It needs urgent assessment, blood cultures and IV antibiotics within an hour, as infection can progress to sepsis rapidly. Growth factor injections (G-CSF) may be used to prevent neutropenia with some regimens.

Nausea and vomiting

Modern anti-sickness medicines, given before chemotherapy and for several days after, prevent nausea in most people. Types include acute (within 24 hours), delayed (days 2 to 5) and anticipatory nausea (before treatment, from conditioned anxiety).

Mouth sores (mucositis)

Mucositis causes painful sores and redness in the mouth and throat, usually 5 to 14 days after treatment. Gentle mouth care, bland rinses and pain relief help.

Fatigue

Cancer-related fatigue is the most common side effect and is not fully relieved by rest. Light regular exercise, good sleep habits and treating anemia help.

Hair loss

Hair usually starts falling out 2 to 4 weeks after starting some drugs and regrows 3 to 6 months after treatment ends, sometimes with a different texture or color. Scalp cooling can reduce hair loss with some regimens.

Gut problems

Diarrhea, constipation, appetite loss and taste changes are common.

Skin and nail changes

Dryness, rashes, darkening of skin or nails, sun sensitivity and hand-foot syndrome (red, painful palms and soles) with some drugs.

Serious and longer-term effects

• Chemotherapy-induced peripheral neuropathy: numbness, tingling or burning in the hands and feet from drugs such as taxanes, platinum agents and vinca alkaloids. It can be long-lasting. Dose changes help prevent it worsening.
• Heart damage: anthracyclines (such as doxorubicin) can weaken the heart muscle, so heart function is monitored.
• Lung damage: bleomycin and some other drugs can cause lung scarring.
• Kidney and bladder damage: cisplatin and ifosfamide, among others.
• Hearing loss and tinnitus: cisplatin.
• Tumor lysis syndrome: rapid breakdown of cancer cells releases salts that can damage the kidneys and heart, mainly in blood cancers.
• Blood clots: increased risk during cancer treatment.
• Infertility and early menopause. Fertility preservation should be discussed before treatment.
• Cognitive changes ("chemo brain"): trouble with memory, attention and multitasking, which usually improves over months.
• Second cancers: a small long-term risk with some drugs.
• Extravasation: some drugs damage tissue if they leak from the vein during infusion.

How side effects are monitored

Before each cycle, your team checks blood counts, kidney and liver function, and asks about symptoms. Heart scans, hearing tests or lung tests are done for specific drugs. Side effects are graded by severity, which guides whether doses are delayed or reduced.

Managing side effects

• Anti-sickness medicines taken exactly as prescribed, including on days you feel fine
• G-CSF injections to boost white cells when needed
• Blood or platelet transfusions for severe anemia or low platelets
• Mouth care: soft toothbrush, salt or baking soda rinses, avoiding alcohol mouthwashes
• Diet: small frequent meals, plenty of fluids, and dietitian support
• Exercise: walking and light activity reduce fatigue
• Infection prevention: handwashing, avoiding sick contacts, food safety, and checking your temperature if you feel unwell
• Vaccines: flu and COVID-19 vaccines as advised; avoid live vaccines during treatment
• Psychological support for anxiety and low mood

Outlook

Most short-term side effects fade within weeks to months after chemotherapy ends. Some, such as neuropathy, fatigue, heart effects and infertility, can persist. Survivorship clinics follow people after treatment to manage late effects.

Frequently asked questions

What are the most common side effects of chemotherapy?

The most common are tiredness, nausea and vomiting, hair loss, mouth sores, appetite and taste changes, diarrhea or constipation, and low blood counts that increase the risk of infection, anemia and bruising. The exact effects depend on the drugs used.

What is neutropenic fever and why is it dangerous?

Neutropenic fever is a temperature of 38 °C (100.4 °F) or higher when white blood cells are low after chemotherapy. Without enough white cells, infections can spread quickly and become life-threatening, so it needs immediate assessment and IV antibiotics.

How long do chemotherapy side effects last?

Most short-term effects such as nausea, mouth sores and low blood counts improve within days to weeks of each cycle and after treatment ends. Hair regrows in 3 to 6 months. Nerve damage, fatigue and some organ effects can last months to years.

Can chemotherapy side effects be prevented?

Many can be prevented or reduced. Anti-sickness medicines prevent most nausea, G-CSF reduces neutropenia, scalp cooling can limit hair loss, and dose adjustments help prevent nerve damage. Good mouth care and staying active also help.

What are the long-term side effects of chemotherapy?

Long-term effects can include peripheral neuropathy, heart or lung damage, hearing loss, infertility, early menopause, cognitive changes and a small risk of second cancers. Survivorship care monitors and treats these effects after treatment.