Chemotherapy is medication used to kill cancer cells. It's generally used in combination with other treatments such as surgery, radiation therapy or biological therapy, though in some cases it may be the only treatment.
Chemotherapy used to make a tumor smaller before surgery or radiation is called neoadjuvant therapy. When used after surgery or radiation, it is called adjuvant therapy. Chemotherapy used solely to relieve cancer symptoms is called palliative therapy. 
According to the <a href="[BASEDOMAIN]/healthinfo/bouncelink.aspx?shortcut=nci" target="_blank">National Cancer Institute</a>, chemotherapy can destroy cancer cells that remain after surgery, shrink tumors, improve survival, prevent cancer from spreading or returning, relieve pain or pressure from tumors, and kill cancer cells that have spread. 
Where it's done 
People may receive chemotherapy in a doctor's office, during an appointment at a hospital or at home. But because of the delicate balance that must be maintained between too little and too much treatment&mdash;between providing enough to kill cancer cells but not so much as to overly damage healthy cells&mdash;people may sometimes be briefly hospitalized for monitoring. 
How it's given 
Chemotherapy drugs may be taken by mouth; given in a shot; placed directly into a vein, artery, body cavity or tumor; or rubbed into the skin as a lotion or cream. 
Chemotherapy may be taken every day, every week or every month. It may be directed at the entire body or at a single organ or area. 
Decisions about which treatment is best depend on such things as the type of cancer, the goal of treatment, the type of medicine, how a person's body responds to treatment, and where in the body cancer cells or tumors are found. 
Most chemotherapy is given in cycles: a treatment period followed by a recovery period, another treatment and recovery period, and so on. 
Side effects 
Side effects from chemotherapy may vary. Common side effects include: 
<ul>
 <li>Fatigue. </li>
 <li>Hair loss. </li>
 <li>Poor appetite. </li>
 <li>Mouth sores. </li>
 <li>Bleeding and bruising easily.</li>
 <li>Anemia.</li>
 <li>Lowered resistance to infections. </li>
 <li>Nausea. </li>
 <li>Vomiting. </li>
 <li>Diarrhea.</li>
 <li>Constipation.</li>
 <li>Mood changes.</li>
 <li>Weight changes.</li>
 <li>Fertility problems.</li>
 <li>Changes in sexual function.</li>
</ul>
Most side effects disappear during the recovery period after treatment stops. Some can be controlled or prevented by medication or other means during treatment. Tell your doctor about all of the side effects you have. 
What you can do 
Throughout chemotherapy, be sure to eat well, avoid people with contagious illnesses and get plenty of rest. If you feel sad, angry or scared, remember that talking about your feelings with a loved one or in a support group can help. 
Reviewed 4/10/2024

Understanding chemotherapy

Chemotherapy is often used to treat cancer. If your doctor recommends this treatment, there may be side effects to watch for. Tell your doctor about any persistent side effects.