Chemotherapy

Chemotherapy uses strong medicines to kill fast-growing cancer cells, and most of its side effects can be prevented or treated.

Rosa: Hi, I'm Rosa. The word chemo can sound scary, but there is a lot your team can do to keep you comfortable. Let me explain how it works and what to expect.

Chemotherapy, often called chemo, is a group of medicines that kill cancer cells or stop them from dividing. There are many different chemo drugs. Your care team picks them based on the type of cancer, its stage, and your overall health.

Chemo works by attacking cells that grow and divide quickly. Cancer cells do this a lot. Think of chemo as a weed killer for fast-growing weeds. It works well on the weeds, but it can also harm some healthy plants that grow fast, like hair roots, the lining of the mouth and gut, and the bone marrow that makes blood cells. That is why side effects happen.

Chemo can be given in different ways: through a vein (IV), as a shot, or as pills you take at home. Many people get a port, a small device placed under the skin of the chest, to make IV treatments easier. Chemo is usually given in cycles. A cycle is a treatment day or days followed by a rest period so your body can recover. A full course often lasts a few months, but this varies a lot.

Chemo can have different goals. It may be used to cure the cancer, to shrink a tumor before surgery or radiation, to lower the chance the cancer comes back after surgery, or to control the cancer and ease symptoms. Ask your care team what the goal of your treatment is.

Side effects depend on the drugs you get. Common ones include tiredness, nausea, hair loss, mouth sores, diarrhea or constipation, and a higher risk of infection. Not everyone gets every side effect. Today there are good medicines to prevent nausea. Most side effects go away after treatment ends, though some, like numbness in the hands and feet, can last longer.

Call your care team right away for a fever of 100.4°F (38°C) or higher, chills, vomiting or diarrhea that will not stop, being unable to keep fluids down, bleeding or unusual bruising, new shortness of breath, or pain or swelling where the IV went in. A fever during chemo can be an emergency because your body may have fewer germ-fighting cells. If it feels very bad, call 911.

Getting ready

Ask for a written schedule, a list of your chemo drugs, and the side effects to watch for. Ask who to call after hours. Fill prescriptions for anti-nausea medicine before your first treatment.

Blood counts

Chemo can lower your white blood cells, red blood cells, and platelets. You will have blood tests before each cycle. Some people get growth factor shots to help white blood cells recover faster.

What helps

Take anti-nausea medicine as prescribed, even before you feel sick. Eat small meals, drink plenty of fluids, wash your hands often, use a soft toothbrush, and stay as active as you can. Short walks can help with tiredness.

Chemo pills at home

Oral chemo is still chemo. Take it exactly as directed. Ask how to store and handle it safely, and what to do if you miss a dose or throw up after taking it.

Questions to ask

What is the goal of this chemo? How many cycles will I get? Which side effects are most likely with my drugs? When should I call you, and what number do I use at night?

Other medicines

Tell your care team about every medicine, vitamin, herbal product, and supplement you take. Some can change how chemo works or raise side effects.

Myth: Everyone on chemo is sick all the time

Fact: Many people have mild side effects and keep up with daily life. Anti-nausea medicines have improved a lot. Tell your team about any side effect so they can help.

Myth: Hair loss happens with every chemo

Fact: Some chemo drugs cause hair loss and many do not. Ask about your specific drugs. For some treatments, scalp cooling may help reduce hair loss.

Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.