Home › Drugs › Chemotherapy
Chemotherapy: how these drugs work
Chemotherapy, or chemo, is one of the oldest and most studied cancer treatments, and it's still a key part of care for many people today. Chemo drugs work by damaging cells that divide quickly. Cancer cells divide fast, so they're hit hardest, but some healthy fast-growing cells are affected too. These include cells in hair follicles, the lining of the mouth and gut, and the bone marrow, where blood cells are made. That's why hair loss, mouth sores, nausea, diarrhea, and low blood counts are such familiar chemo side effects. The good news is that most of these healthy cells recover once treatment ends, and today's anti-nausea medicines and supportive care make chemo much easier to get through than it was even 15 years ago.
ℹ️ General information to help you and your loved ones talk with your care team, not medical advice. Read our disclaimer.
On this page: IV chemotherapy · Chemotherapy pills
IV chemotherapy
Most chemo is given into a vein (IV), through a port, or a PICC line, at an infusion center. The drugs on our site come from several families. Platinum drugs, like carboplatin, cisplatin, and oxaliplatin, damage DNA. Taxanes, like paclitaxel, docetaxel, and Jevtana (cabazitaxel), stop cells from splitting in two. Others include antimetabolites (fluorouracil, gemcitabine, and pemetrexed), which disguise themselves as building blocks of DNA, topoisomerase inhibitors (irinotecan and etoposide), and anthracyclines (doxorubicin). Each family has its own typical side effects. For example, oxaliplatin is known for cold-triggered tingling, and the taxanes for numbness and hair loss.
Chemotherapy pills
Some chemo comes as a pill you take at home. Capecitabine turns into fluorouracil inside the body, and Lonsurf (trifluridine and tipiracil) works in a similar way. Pills are convenient, but they're still chemo, with the same need for blood tests and the same care in handling. Wash your hands after touching them, and ask your pharmacist how to store and dispose of them safely. Capecitabine is known for hand-foot syndrome (red, sore palms and soles). Our hand-foot syndrome guide has tips.
Why chemo is given in cycles
Chemo is usually given in cycles: a treatment day, or a few days, followed by a rest period of one to several weeks. The rest lets healthy cells, especially blood cells, recover before the next dose. Your blood counts are checked before each cycle, and a dose may be delayed if counts are still low. That's a normal safety step, not a setback.
Chemo is often combined
Most chemo for these cancers is given as a regimen, a set combination of drugs, sometimes with immunotherapy or a targeted drug. For example, FOLFOX for colorectal cancer combines fluorouracil, leucovorin, and oxaliplatin. Our regimen guides explain the most common ones day by day.
Side effect guides that may help
- Neutropenia (low blood counts and infection risk)
- Nausea and vomiting (CINV)
- Alopecia (hair loss from chemo)
- Fatigue (extreme tiredness)
- Mucositis (mouth sores)
- Neuropathy (numbness and tingling)
- Diarrhea (loose, watery stools)
❓ Questions you and your loved ones can ask
- What is the goal of this treatment for me?
- How will we know if it's working?
- Which side effects should I call about right away, and what number do I call after hours?
- Which medicines, vitamins or supplements should I avoid?
- Will this affect my ability to work, drive, or care for my family?
- What will this cost me, and who can help me with coverage?
Written by the CSE Team from FDA labels and leading cancer centers. Not medical advice. · Last updated: October 15, 2026 · How we write
Sources
Last updated: October 15, 2026. We summarize these sources in our own words.