There are "major issues" over the way doctors document drug alleries that could be putting patients at serious risks, according to health experts.
The National Institute of Health and Care Excellence (Nice) said "insufficient information" about patients' allergies was being shared among healthcare workers.
Nice's guidelines say doctors should check if patients are allergic to any drugs.
Nice said prescriptions should be redesigned and standardised to record information on which drugs should be avoided to reduce the risk of drug allergy.
New guidelines also say doctors should check patients' allergy status before prescribing, dispensing or administering any drug.