Can you eat mouldy food? What's safe and what's not

We've all looked at white spots on cheddar or blooms of fur on bread and wondered if it's worth the risk. With some 6.6 million tonnes, external of food thrown away by households in the UK every year, here's what's safe to salvage – and what should go straight in the bin.

Food mould is made up of microscopic fungi. It grows as a network of threads called mycelium, which works its way through food like plant roots. When their spores break through the surface, food can change colour and get a dusty appearance.

Some of our favourite foods are made using safe moulds. Penicillium roqueforti, external gives blue cheeses their blue veins and strong flavour. Botrytis cinerea, or 'noble rot', is used in winemaking, external to reduce the grapes' water content and enhance their sweetness.

But that doesn't mean we can eat anything that's mouldy. Different moulds affect people differently, and if you've a mould allergy you have to be particularly careful.

The Food Standards Agency (FSA) advises against eating any food containing mould, external, particularly for children, older people and those who are pregnant or have a weakened immune system.

Mould expert, Dr Patrick Hickey, says some food can be salvaged "but do so at your own risk".

"Moulds tend not to cause sudden food poisoning", says Hickey, but some moulds produce toxins called mycotoxins.

If you consume a lot of these, "it may cause gastro-intestinal symptoms and more serious effects, including liver or kidney failure and death".

Some moulds, including Aspergillus, external, found on damp grain or nuts, produce aflatoxins, external linked to liver cancer.

While it's rare for humans to get acutely poisoned, Hickey says there's not much known about the long-term effects of eating small amounts of fungal toxins, warning "there's concern that if consumed repeatedly, mycotoxins may cause cumulative effects and lead to illness".

The FSA says you shouldn't eat mouldy bread, as porous food can be contaminated below the surface, external.

"As a general rule, a mould colony of 1cm in diameter on the surface has also penetrated 1cm deep into the food", says Hickey.

If your loaf is turning stale but not mouldy, you can use it to make breadcrumbs or croutons.

Cheddar and Parmesan resist mould well, as they don't provide the moist conditions it needs to spread. "If you find mould colonies on hard cheese that are smaller than 5mm, take at least 10mm off all sides before eating", recommends Hickey. But be sure to keep the knife out of the mould so it doesn't contaminate other parts of the cheese.

Soft cheeses or any that can be spread or crumbled are different. Unless the fungus has been deliberately introduced, like in blue cheese, throw these cheeses away if mouldy. The higher water content means microbes grow quickly, which can lead to food poisoning from bacteria such as salmonella or listeria, external.

Firm fruit and veg with little spots of mould can usually be saved – as long as they're not slimy, as this signals the presence of bacteria that can cause food poisoning or stomach pain.

Cut at least 1cm around and below the mouldy area on firm veg (like root veg and cabbage) before eating. Their low moisture content and often higher acid levels make it harder for the mould to penetrate.

Be wary of apples. A toxin called patulin, external can be found in damaged or mouldy apples, so never drink mouldy apple juice.

Soft fruit and veg, such as cucumbers, tomatoes and peaches, should be thrown away, as their high moisture content means they're more likely to be contaminated below the surface, external.

Slightly wilted salad leaves will be okay to eat, but avoid any that have turned mouldy or slimy.

The FSA warns that "while it's possible that removing the mould and a significant amount of the surrounding product could remove any unseen toxins that are present, there's no guarantee".

Hickey suggests if your jam has a bit of green mould on the surface, it should be safe to eat if you scoop out the top layer and a few centimetres beneath and eat as soon as possible, but the mould will likely return after a few days.

If you're unsure, or the jam has a thick layer of mould, it's best to bin it. The same applies to jars of curry paste.

You can't prevent your food going mouldy, but you can slow the process down. Mould likes warm, damp conditions with plenty to feed on. A clean, dry and well-ventilated kitchen can help keep mould at bay.

How you store your food can make all the difference – keep salad leaves in airtight containers lined with paper towel in the fridge.

Originally published April 2021. Updated March 2026.

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