Three people from the same household have been hospitalised after suffering from possible death cap mushroom poisoning.

The ACT Health Department was investigating the patients' claims they ate mushrooms bought from a Woolworths store in the Canberra suburb of Dickson more than a week ago.

Death cap mushroom facts The death cap mushroom, Amanita Phalloides, is a poisonous fungus responsible for 90 per cent of all deaths related to mushroom consumption.

The death cap mushroom, Amanita Phalloides, is a poisonous fungus responsible for 90 per cent of all deaths related to mushroom consumption. The mushrooms often grow near established oak trees, and are found during warm, wet weather.

The mushrooms often grow near established oak trees, and are found during warm, wet weather. The mushrooms' caps are 40-160mm wide, usually pale green to yellow in colour, with distinctive white gills.

The mushrooms' caps are 40-160mm wide, usually pale green to yellow in colour, with distinctive white gills. The cap may be be slippery and sticky to touch and shiny when dry.

The cap may be be slippery and sticky to touch and shiny when dry. One mushroom has enough poison to kill an adult.

One mushroom has enough poison to kill an adult. All parts of the mushroom are poisonous; cooking or peeling does not make the mushroom safe to eat. Source: ACT Health

A spokeswoman for ACT Health said the incident was being treated as isolated and there were no other reported cases of illness.

Anyone who ate mushrooms bought from Dickson Woolworths around April 17 and was experiencing symptoms of stomach aches, vomiting and diarrhoea have been advised to seek immediate medical attention.

"Three patients from the same household have presented to Calvary Hospital in the last 48 hours with possible death cap mushroom poisoning," the ACT's chief health officer, Paul Kelly, said in a statement.

"If people still have mushrooms that were purchased from Woolworths Dickson around this time they are recommended to discard them.

"People are reminded not to pick and eat any wild mushrooms. It can be extremely difficult for even experienced collectors to distinguish death cap mushrooms from other edible mushrooms."

One of the three people with suspected death cap mushroom poisoning was transferred from Canberra to a Sydney Hospital. Their condition is unknown.

The other two people remain in a stable condition in hospital.

Woolworths said in a statement there were no other similar reports of food poisoning but it took customer safety seriously and was working closely with ACT Health.

The company says its produce is subject to strict government controls and is regularly monitored.

Acting chief health officer Dr Rahil Appuhamy said mushroom poisoning could be fatal.

"Death cap mushrooms can be quite severe in some patients," he said.

"They can start with symptoms like nausea, vomiting and diarrhoea, but they can progress on to liver failure and sometimes, unfortunately, death. But fortunately the patients are currently stable."

Symptoms of poisoning generally appear between six and 24 hours after ingesting death cap mushrooms.

Two people died from death cap mushroom poisoning in Canberra in 2012.