Why side‑effects occur

Chemotherapy drugs target rapidly dividing cells, which include cancer cells but also some normal cells in the bone marrow, mouth, gut, hair follicles and reproductive organs. Damage to these normal cells can cause side‑effects such as low blood counts, mouth sores, hair loss, diarrhoea or constipation, and fatigue.

Everyone reacts differently. Some people have many side‑effects, others very few, even on the same drugs.

Nausea and vomiting

Modern anti‑nausea medicines have greatly reduced this problem, but it can still occur.

Tips that may help:

• Eat small, frequent meals instead of large ones.
• Sip clear fluids such as water, tea or diluted juices through the day to stay hydrated.
• Avoid heavy, greasy or strongly smelling foods when you feel queasy.
• Take anti‑nausea tablets exactly as prescribed, even if you feel well – they often work best when taken before symptoms start.

Tell your team if nausea is not controlled; there are several drug options that can be adjusted.

Fatigue (tiredness)

Feeling unusually tired is one of the most common side‑effects of chemotherapy.

Helpful strategies include:

• Balancing light activity (like a short walk) with rest breaks.
• Taking short naps of 15–30 minutes rather than long daytime sleeps so you can still rest at night.
• Asking family or friends for help with heavy chores or childcare.
• Focusing your energy on the most important tasks and letting less urgent things wait.

Severe or persistent fatigue can be a sign of anaemia or other problems, so mention it to your doctor, especially if it suddenly worsens.

Low blood counts and infection risk

Chemotherapy can lower white blood cells (infection fighters), red cells (which carry oxygen) and platelets (which help blood clot). You may not feel anything when counts drop, so regular blood tests are essential.

Call your team urgently if you have:

• Fever of 38 °C (100.4 °F) or higher
• Chills or shaking
• New cough, sore throat or burning when passing urine
• Unusual bleeding or bruising

To reduce infection risk:

• Wash hands often; avoid close contact with people who are sick.
• Clean cuts promptly and keep them covered.
• Ask before getting any vaccines during treatment.

Mouth sores and taste changes

Some chemotherapy drugs can irritate the lining of the mouth and alter taste.

• Brush gently with a soft toothbrush and use mild mouthwashes recommended by your team.
• Avoid very hot, spicy or acidic foods if your mouth is sore.
• If foods taste metallic, try eating with plastic cutlery or adding marinades and herbs to improve flavour.

Report mouth pain that makes it hard to eat or drink; medicines and mouth rinses can help.

When to seek help

Your oncology team wants to know about side‑effects early so they can help keep treatment on track. Call them if you are unsure whether a symptom is serious. Many issues can be managed with medicines, dose adjustments or supportive therapies such as diet changes, counselling or complementary approaches like relaxation exercises.