Statins and hayfever pills could be fuelling antibiotic resistance by changing the growth of bacteria in the human gut, scientists have found.

Researchers from the European Molecular Biology Laboratory (EMBL) looked at the impact of 1,000 common drugs on the 40 strains of gut bacteria and found that one quarter were having a negative impact.

Among those discovered to be harmful were simvstatin, one of the commonest statins, the breast cancer drug tamoxifen and the common hayfever medication loratidin.

The researchers warn that taking everyday pills may promote antibiotic resistance, as they encourage unhelpful bacteria to develop new resistant strains in the same way as antibiotics.

"This is scary," said Dr Nassos Typas, of EMBL Heidelberg, Germany. "Considering that we take many non-antibiotic drugs in our life, often for long periods.

"We actually see drugs from all therapeutic classes impacting gut microbes. The most prominent from them are antipsychotics, antihypertensives, anti-cancer drugs, proton-pump inhibitors, antihistamines, painkillers and contraceptives."

Around 5,000 people in England die each year because antibiotics have become useless against some infections and experts predict resistance will kill more people than cancer and diabetes combined within 30 years.