Chemotherapy: How It Works and How You'll Feel

Chemotherapy is a treatment for cancer that uses powerful drugs to destroy cancer cells. Unlike radiation or surgery, which target specific areas, chemo can work throughout your body. It targets cells that grow and divide quickly, as cancer cells do. But it can also affect some fast-growing healthy cells, like those of the skin, hair, intestines, and bone marrow. That’s what causes some of the side effects from the treatment.

Getting Ready for Chemotherapy

Your chemotherapy plan will be tailored to your specific disease. You might get just one drug or a few different ones. You might go through one treatment cycle or more. Chemo might be your only cancer treatment, or you might get it along with others such as surgery or radiation.

You and your doctor will decide together the treatment that's best for you based on:

  • The type of cancer you have
  • How large your tumor is and how far it has spread, called the stage of your disease
  • How healthy you are overall
  • Any cancer treatments you’ve had before
  • Your goals for your care

Keep a list of any questions you have about chemo, and bring it when you visit your doctor. To help you remember details, you may want to bring a relative or friend to your appointments.

Bring a list of all the medications and supplements you take, too, since they can change the effects of chemo. Your doctor can tell you if you should stop taking any of those drugs before your treatment begins. And tell your doctor about any health problems you have before you start.

How You Get Chemotherapy

Depending on the type of chemo drugs you will take, the dose, your treatment center, and your insurance, you might get your therapy in any of the following places:

  • Your home
  • The doctor's office
  • The hospital
  • The hospital's outpatient unit
  • A clinic

How you will take it depends on the type of drug you need. You could get it as:

  • A pill or capsule to swallow
  • A cream or gel you put on your skin
  • An injection or infusion into a vein


In some cases, you might need to get a drug through a catheter, which is a thin tube a surgeon puts into a large vein, often in the chest. The tube will stay in place until chemotherapy is over.

In some cases, the catheter is attached to a small disk under your skin called a port. A nurse will put a needle into the port to deliver the drug.

Doctors can also put the drug directly into the tumor, either as an injection or a small disk implanted near the tumor that releases the drugs over time.

How Long Chemotherapy Takes

The length of treatment varies. Whatever your plan is, it’s important to follow it precisely. The doctor will tell you exactly how much of a drug you need and when you’ll get it. That means you can't skip appointments, or if you’re getting your chemo at home, you can’t change the amount or timing of your medication.

Usually, the doctor will prescribe a specific number of cycles for your treatment. A cycle is the number of days you take a drug and the number of days you don't. For example, your cycle may be 3 weeks long -- 2 weeks of daily chemo followed by 1 week of no therapy. The time without therapy is important because it gives your body’s healthy cells a chance to recover.

Depending on how your body reacts to treatment, your doctor may make changes to your plan.

Side Effects

Talk with your doctor about how chemo might make you feel before you start therapy. Some people don’t have any side effects, but most will have at least some. The way the treatment affects you will depend on many things, including the drug you take, how healthy you are overall, and the type and stage of cancer you have.

There are some common side effects that usually go away once treatment is over. They include:

  • Fatigue
  • Nausea
  • Bowel and bladder problems
  • Hair loss
  • Infections

Longer-lasting side effects can include sexual and fertility problems and nerve damage.

There are almost always ways to handle these problems to help you feel better. Talk to your doctor about what to expect on the day of treatment as well as after it’s over.

WebMD Medical Reference Reviewed by William Blahd, MD on June 27, 2016



American Cancer Society: "Understanding Chemotherapy: A Guide for Patients and Families."

Mayo Clinic: "Chemotherapy: What you can expect."

MedlinePlus: "Chemotherapy."

National Cancer Institute: "Chemotherapy and You: Support for People With Cancer."

© 2016 WebMD, LLC. All rights reserved.