A line in this column questioning why vaccine-related side-effects receive so much media coverage while thousands of deaths caused by the ibuprofen family of anti-inflammatory drugs go almost unreported has prompted a huge response from readers wanting to know more — so here is the story in more detail.

Non-steroidal anti-inflammatory drugs (NSAIDs) alleviate pain, soothe inflammation and reduce fevers, making them a popular choice for treating everything from flu to back pain and arthritis. Aspirin was the first member of the family to be identified but today the most widely used NSAIDs are ibuprofen (in Nurofen, Brufen and Anadin Ultra) and diclofenac (Voltarol and Fenactol).

NSAIDs work by blocking the production of chemical messengers (prostaglandins) that prompt an inflammatory response when the body is attacked or injured. They moderate this response without seeming to have a significant adverse effect on the body’s ability to defend and repair itself — or, to put it another way, taking ibuprofen for your back pain won’t slow your recovery.

But prostaglandins play a crucial role in other processes in the body, particularly in the upper part of the gut, where they help to protect the stomach lining against corrosive digestive juices. And herein lies the problem: they weaken the stomach’s defences, leading to ulceration and stomach haemorrhages that kill as many as 2,500 people in the UK every year and put many thousands more in hospital.

Indigestion is often an early clue but in many cases there are no warning symptoms and a catastrophic bleed may be the first sign of trouble. One elderly patient of mine ended up in hospital with a bleed just 72 hours after I started him on diclofenac for his arthritic hip.

Cases such as this are unusual, and the vast majority of the millions of people who take NSAIDs will have no problems. But these drugs still exact a worrying toll that could be reduced significantly if the latest guidance were followed.

NSAIDs should be avoided in those at the highest risk (such as people who have had a previous stomach bleed) and prescribed with other drugs to protect the lining of the stomach in those deemed to be at above-average risk (such as anyone over the age of 65 and those already on low-dose aspirin).

The standard protective drug used in the UK is omeprazole, which reduces acid production, but studies suggest that about three quarters of people who should be prescribed it are not. If you think that you may be one of them, make sure you raise the issue when your repeat prescription comes up for renewal.

But bleeds are not the only worrying side-effect of NSAIDs. They also cause fluid retention and put a strain on the kidneys, which makes them a poor choice for anyone with high blood pressure, heart failure and/or weak kidneys. And they have been linked to heart attack and stroke.

Recent research that attempted to quantify the additional risk for people most likely to have a heart attack (those aged 65 or over) estimated that 1,005 of these highest-risk patients would have to take ibuprofen for a year for it to lead to one additional heart attack. The findings may change the prescribing habits of doctors faced with patients most likely to have a stroke or heart attack, but the rest of us need not be overly concerned. If you take ibuprofen on an ad hoc basis for back ache, hangovers, etc, there is no need to change your practice. Even if you are on a regular NSAID for a problem such as arthritis, the benefits of day-to-day relief from pain and stiffness almost certainly outweigh the small extra risk of heart problems.

NSAIDs have also been linked to miscarriage and sub-fertility. Prostaglandins play an important role in ovulation and the implantation of any resulting fertilised egg into the wall of the womb, so are best avoided by pregnant women and those trying to conceive. They also delay the onset of labour and increase its duration, and can sometimes alter the developing baby’s circulation, increasing the risk of long-term heart and lung problems. Paracetamol remains the painkiller of choice during pregnancy.

For more detailed information, type NSAIDs into the search engine on the homepage of www.patient.co.uk

E-mail questions to drmark@thetimes.co.uk or write to times2, 1 Pennington Street, London E98 1TT