Asked by: Emily Thompson, Stockport
The antibiotic penicillin is made from the fungus Penicillium chrysogenum. Stilton and most other blue cheeses do use Penicillium mould to create the blue veins, but they use a different strain (P. roqueforti) and the whole mould, rather than the penicillin extract.
It is possible to be allergic to the drug and still be able to eat the cheese with impunity, although there are also people who are allergic to both. It’s also worth noting that only 20 per cent of people who think they are allergic to penicillin, actually are.