Deadly wild mushrooms are growing across Victoria, with health authorities urging people not to pick or eat them.

Victorians are being warned not to pick or eat wild mushrooms as heavy rain has led to the growth of deadly varieties.

Autumn conditions and a recent deluge of rain has created ideal growing conditions for poisonous mushrooms including the death cap and yellow-staining varieties, the state health department warned on Tuesday.

The most dangerous variety - the death cap - has been found in both suburban Melbourne and rural areas, most commonly near oak trees.

"The death cap is extremely toxic and responsible for 90 per cent of all mushroom poisoning deaths," Victoria's chief health officer Charles Guest said in a statement.

Symptoms of death cap poisoning start with nausea, abdominal pain and diarrhoea before the toxin attacks the liver, with death usually within 48 hours.

"Anyone who becomes ill after eating mushrooms should seek urgent medical advice and, if possible, take samples of the whole mushroom for identification," Prof Guest said.

He urged people to buy mushrooms rather than pick their own, as they may not be able to distinguish the difference between poisonous and safe varieties.

Death caps are large-sized mushrooms which range from light olive green to a yellow-green colour, while yellow-staining mushroom turns yellow when the cap or stem is bruised by a finger.

"If you have any doubts about a species of fungus or mushroom, don't eat it," Prof Guest said.