Side Effects of Cancer Treatment

Most side effects can wait for your next appointment. A fever during treatment cannot.

• Call your care team straight away, day or night, if your temperature reaches 100.4°F (38°C) or higher. If you cannot reach them quickly, go to an emergency department. Also call if you feel shivery, shaky, or suddenly unwell even with a normal reading. During chemotherapy, your white cell count can be too low to fight infection. CDC calls a fever during chemotherapy a medical emergency, not something to sleep off.
• Call 911 or go to an emergency department for sudden shortness of breath, chest pain, heavy bleeding, confusion, a seizure, or a sudden inability to keep fluids down.

Do not take acetaminophen or ibuprofen to bring a temperature down before you call. It can hide the fever your team is trying to measure. Keep the out-of-hours number your team gave you somewhere you can find it at 3am.

Cancer treatments and cancer itself can cause side effects. A side effect is a problem that happens when treatment affects healthy tissues or organs, not just the cancer cells. Because treatment reaches normal parts of the body too, it can cause new problems while it works against the cancer.

The most important thing to know: your health care team can help. They can treat many side effects, or talk with you about ways to reduce them, so you feel better.

Cancer treatments are designed to destroy or slow cancer cells. But healthy cells and organs can be affected along the way. When that happens, you may notice problems such as tiredness, an upset stomach, or changes in how you eat. These are side effects.

The cancer itself can also cause problems that feel like side effects. So the two can overlap.

Side effects vary from person to person, even among people receiving the same treatment. You might have side effects that a friend or family member with cancer never had. The opposite can be true too. There is no single way that treatment affects everyone.

Because of this, it helps to focus on your own experience rather than comparing yourself with others.

Tell your doctor about side effects you are having, so you get the care you need to manage them. Speaking up early is one of the most helpful things you can do.

Your health care team can:

• Treat the side effect directly.
• Suggest ways to prevent it or make it less severe.
• Adjust your care so you feel better day to day.

You do not have to simply "put up with" side effects. Reporting them is part of good care.

Your team needs to know everything you take, not just prescriptions. That includes over-the-counter medicines, vitamins, minerals, herbal products, and fish oil. Ask whether any of them could change the way your cancer treatment works.

Ask too whether the treatment could affect your ability to have children. Some options for protecting fertility have to be arranged before treatment begins, so this is a question worth raising early rather than later. See fertility and cancer treatment.

There are many possible side effects. Which ones you may have depends on your treatment and your body. Some of the ones NCI describes include:

• Fatigue, meaning extreme tiredness.
• Hair loss, called alopecia.
• Nausea and vomiting.
• Pain.
• Appetite loss and weight changes.
• Anemia, meaning too few red blood cells.
• Infection.
• Constipation, diarrhea, and other digestion problems.
• Mouth and throat problems.
• Nerve problems.
• Skin and nail changes.
• Sleep problems.

For symptom-specific help, start with the page closest to what is happening: diarrhea during cancer treatment, constipation during cancer treatment, mouth sores, nausea, fatigue, appetite loss, taste changes, hair loss, neuropathy, rash, fever during chemo, low white blood cells, and immune-related side effects.

These guides focus on what to track, what to ask, and which red flags are worth discussing with your care team before symptoms become harder to manage.

Learning what to expect can make side effects feel less frightening. It can also help you know when to reach out to your team.