TWO types of commonly-prescribed antibiotics could put patients at risk of dangerous skin rashes, a new study warns.
Scientists say the pills, used to treat conditions like UTIs and pneumonia, can lead to side effects with life-threatening consequences.
They are now urging doctors to use lower-risk alternatives.
Researchers looked at data from more than 100,000 people aged 66 and over who were prescribed oral antibiotics at least once between 2002 and 2022 in Ontario, Canada.
Within 60 days of taking the drugs, 21,758 patients visited A&E or were hospitalised due to severe skin rashes, known as cutaneous adverse drug reactions (cADRs), which can also affect the organs.
These can appear straight after taking a medication, or sometimes weeks later.
Scientists found there were two cADR-related hospital visits for every 1,000 antibiotic prescriptions dispensed, and about one in eight patients who visited A&E with antibiotic-related cADRs were hospitalised.
Of those who were admitted, 20 per cent were treated in the ICU, and five per cent died.
A fifth of hospitalised patients with the most severe reactions were treated in a critical care unit, and they had an in-hospital mortality rate of 20 per cent.
Serious cADRs usually start with red, scaly patches that are itchy and can feel like they’re burning, but they can trigger dangerous immune system reactions if left untreated.
This includes drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN), also known as Lyell’s syndrome, which is the most severe.
It carries a mortality rate of 20 to 40 per cent, the authors said.
In rare cases, these reactions can result in sepsis or septic shock – a life-threatening response to an infection, including dangerously low blood pressure, which can lead to organ failure and death.
Scientists found the antibiotics most likely to cause cADRs were sulfonamides, also known as sulfa drugs, and cephalosporins.
As well as penicillin, cephalosporins are among the most commonly prescribed antibiotics – used to treat conditions like urinary tract infections (UTIs), pneumonia, meningitis and peritonitis, according to the National Institute for Health and Care Excellence (NICE).
Sulfa drugs, including trimethoprim, are prescribed for UTIs, inflammatory bowel disease, malaria and various skin, eye and vaginal infections.
All antibiotics in the study – which included penicillins, cephalosporins, fluoroquinolones, nitrofurantoin, and sulfonamides – were associated with a higher risk of serious cADRs relative to macrolides (a class of drugs used to manage and treat various bacterial infections), but sulfonamides and cephalosporins were linked to the the highest risk.
Patients should be aware of rash, fever, and other symptoms, which can start weeks after a prescription has been started and even after the course of antibiotics has stopped
Dr David Juurlink
Dr Erika Lee, an allergist and a trainee with ICES and Temerty Medicine’s Eliot Phillipson Clinician-Scientist Training Program, said: “The good news is that most patients who visited the hospital with these reactions were discharged without being admitted, so that should be reassuring to providers and patients.
“But these findings underscore the need for careful prescribing practices.”
Dr David Juurlink, head of the Division of Clinical Pharmacology and Toxicology at Sunnybrook Health Sciences Centre, added: “While rare, these severe drug reactions can be life-threatening.
“Patients should be aware of rash, fever, and other symptoms, which can start weeks after a prescription has been started and even after the course of antibiotics has stopped.
“It’s also one more reason why antibiotics should be prescribed only when they’re truly needed.”
The findings were published in the journal JAMA Network.
ANTIBIOTICS are usually something you'll come across if you suffer a nasty bug.
The life-saving pills are used by millions every year, for a whole host of issues.
They are specifically used to help our bodies fight off bacterial infections.
And once upon a time, they were handed out relatively freely.
But many countries have joined the fight to prevent antibiotic resistance, the drugs are no longer routinely used to treat all infections.
Antibiotics don’t work for everything and here we take a look at how long it takes them to work and whether or not you need to take the full course.
How long does it take for antibiotics to start working?
Antibiotics start to work straight away — but you might not get them until you’ve felt unwell for a while.
They work by or preventing bacteria from spreading or killing them, the NHS states.
However, they don’t work for viral infections.
This includes colds and flu, Covid, chest infections, ear infections in children, and most coughs and sore throats.
In most cases they will be prescribed to you if the bacterial infection won’t clear up without them or if you could infect others.
Medication could also be given if the infection would take too long to clear on its own or if it carries the risk of more serious complications.
When will I feel better?
Everyone is different – as is their response to antibiotics.
Most people will feel better towards the end of the course, but this varies, and will depend on the drug being taken.
Most antibiotics should be taken for one to two weeks but shorter treatments work just as well in some cases.
Your doctor will decide the best length of treatment and correct antibiotic type for you.
If you have completed the course and don’t see any signs of improvement, talk to your doctor or pharmacist.
Do I need to take my full course of antibiotics?
It can be tempting to stop taking antibiotics as soon as you’re starting to feel better – but doctors say you shouldn’t as it can result in the infection returning.
Doing so also contributes to the growing issue of antibiotic resistance.
If you forget to take an antibiotic, it’s not the end of the world, but take that dose as soon as you remember and carry on with the course of antibiotics as normal.
But if it’s almost time for the next dose, skip the missed one and continue your regular dosing schedule.
Do not take a double dose to make up for a missed one as this can increase the risk of side effects.
What are the side effects?
The NHS states that most commonly, people will feel sick, be sick, have bloating and indigestion, while others also have diarrhoea.
Guidance states that some people might also have an allergic reaction to the medication – especially penicillin and another type of antibiotic called cephalosporins.
