Antimetabolite Chemotherapy: — What to Expect

The lining of your mouth replaces itself every seven to fourteen days, making it one of the fastest-dividing tissues in the body. Antimetabolites work by targeting rapidly dividing cells — they cannot distinguish the mouth lining from a cancer cell. Soreness, ulcers and difficulty swallowing are the result. This is one of the most predictable effects of this class, which is why mouth care starts on day one of treatment and not after soreness appears.

Mild loose motions are common and often settle with fluids and rest. What your team needs to know is the change from your usual pattern — how many more times than normal, whether it is getting worse each day, and whether there is blood, mucus, abdominal pain or fever alongside it. Any of those signs, or loose motions that have not improved after 24 hours, are reasons to call the same day rather than wait. Do not take over-the-counter anti-diarrhoeals before speaking to your team.

Antimetabolites cause less dramatic hair loss than some other chemotherapy classes. Mild thinning is possible with several agents in this group, but complete hair loss is uncommon. If your treatment plan includes other chemotherapy medicines alongside an antimetabolite, those other medicines may contribute more to hair loss than the antimetabolite itself. Your oncologist can tell you what to expect based on your specific regimen.

It depends entirely on which antimetabolite you are on. Some agents in this class — specifically the folate antagonists such as methotrexate and pemetrexed — work partly by blocking the body's use of folate. Adding folic acid without guidance could interfere with how your treatment works, or it may be needed to protect against certain side effects, depending on the medicine and your situation. Do not start or stop folic acid or any supplement without discussing it with your oncologist first.

5-fluorouracil (5-FU) is given by a drip in a day-care or inpatient setting. Capecitabine — sold under names including Xeloda and Capecita in India — is a tablet taken at home that the body converts into 5-FU. Because you are taking capecitabine at home, you are responsible for watching for side effects between clinic visits: hand-foot syndrome, mouth soreness and diarrhoea in particular. Which one suits your situation is a decision your oncologist will explain based on your cancer type and treatment plan.

Most side effects improve within weeks of stopping treatment. Mouth soreness and diarrhoea typically ease as the lining of the mouth and gut recovers. Blood counts usually return toward normal within weeks, though the exact timeline depends on your treatment and your overall health. Fatigue can persist longer. If a side effect is not improving after your treatment ends, tell your team — persistent symptoms deserve assessment rather than waiting to see.