Which painkillers are safe during chemotherapy?

Usually yes, as the first-choice simple painkiller, because it does not affect platelets, the stomach lining or the kidneys the way anti-inflammatories do. The standard adult ceiling is 4 g in 24 hours, and it is lower in several groups — 2 g if you weigh 40 kg or less, 3 g between 41 and 49 kg, and 3 g with liver impairment.

The one hard rule: never take it for a fever before calling your team. It lowers the temperature and hides the signal they need.

Four reasons, all of which are about chemotherapy rather than the drug itself. Anti-inflammatories affect platelets, and chemotherapy can drop your platelet count. They irritate the stomach lining, which steroids already do. They reduce the kidney's own protection, and a meta-analysis identified them as a risk factor for cisplatin-induced kidney injury.

And like paracetamol, they mask a fever. Ask your team before taking any anti-inflammatory, particularly if you are on methotrexate or cisplatin, or your platelets are low.

38°C (100.4°F) or higher is the threshold most sources give for calling immediately, day or night. Some UK services use a sustained reading above 37.5°C, or anything below 36°C, as the trigger.

Use whichever number your own hospital gave you — and either way, call first rather than taking a fever-reducer and waiting to see.

Do not stop it, and do not continue it, on your own. Low-dose aspirin prescribed for heart or stroke protection is a pharmacologically different question from aspirin taken as a painkiller.

It needs a joint decision between whoever prescribed it and your oncology team, and the answer can change depending on your platelet count at that point in treatment.

It is described as unlikely when opioids are properly prescribed and monitored for cancer pain. Needing more over time is tolerance, and having withdrawal symptoms if a drug is stopped abruptly is physical dependence — neither is addiction, which is a behavioural pattern of craving and misuse.

Patients with a past history of substance misuse are monitored more closely rather than refused pain relief. ASCO's 2022 guideline warns specifically against undertreating cancer pain out of fear of addiction.

Constipation is the commonest opioid side effect, and it is predictable enough that a laxative should be started at the same time as the opioid rather than added once the problem appears. ASCO's evidence review found the stimulant laxative senna effective without adding a softener.

Tell your team if it is not working. The answer is almost never to stop the pain relief.

Tell your team before you start or continue anything. Some interactions are documented rather than theoretical: green tea extract binds bortezomib and blocked its anticancer effect in laboratory work, and St John's wort measurably lowered blood levels of irinotecan, imatinib and docetaxel.

Others are only laboratory concerns so far. Either way, “natural” is not the same as “no effect on your chemotherapy”.

Bring the actual packet to your oncology team. Two independent studies published in JAMA found detectable lead, mercury or arsenic in roughly one in five Ayurvedic products tested — 20 per cent in one, 20.7 per cent in the other — with contamination rising to 40.6 per cent in products made by the traditional rasa shastra method that deliberately combines herbs with metals.

This is a contamination risk that exists separately from any interaction with your chemotherapy drugs. It is a reason for your team to see what you are taking, not a reason to hide it.

Salt-water and sodium bicarbonate rinses several times a day are the standard first step, and benzydamine mouthwash is also used. Avoid alcohol-containing mouthwashes.

If you are having bolus 5‑fluorouracil, or high-dose melphalan before a stem cell transplant, ask about sucking ice chips during the infusion — oral cryotherapy is a specific MASCC/ISOO guideline recommendation for those two settings.