Doctors are being told to check patients' diets before prescribing drugs to avoid dangerous cocktails.
Grapefruit is a bad combination with certain drugs
Safety advisors estimate around 200 drugs become toxic, or less effective, when combined with certain foods.
For example, the anti-clotting drug warfarin reacts with cranberry juice and the oral contraceptive may not work if you mix it with St John's wort.
An independent committee will advise the Food Standards Agency and government's medicines regulatory body.
Many people can be taking up to 10 medicines at any one time, so the potential for dangerous and potentially deadly interactions is concerning, says the independent Committee on Toxicity which advises the government.
Grapefruit juice with the cholesterol-lowering statin drugs
St John's wort with oral contraceptive pill or antidepressants
Alcohol with paracetamol or sedatives
Source: Committee on Toxicity
Drugs such as warfarin, which can be toxic unless taken in very precise amounts, are particularly prone to interactions with diet.
Similarly, some foods can be problematic.
A substance found in soy sauce might interfere with the breast cancer drug tamoxifen, scientists believe.
However, most people taking medicines do not have to modify their diet, the committee said in a draft report.
For example, milk and dairy products can reduce the uptake of antibiotics. But all are widely consumed without any obvious problems and any interactions that do occur are unlikely to be life threatening.
Rather than widespread public information, it is therefore most appropriate that practitioners and prescribers should be aware of the potential for drug-food interactions, it said.
A spokesman from the Food Standards Agency said: "GPs and other medical practitioners are really best placed to advise patients about any potential interactions when they prescribe them medicines."
A spokeswoman from the Medicines and Healthcare products Regulatory Agency said important drug-food interactions were included in the prescribing information that comes with medicines.
"We would always advice patients to read the information leaflets that come with drugs."