Health officials are warning people to stay out of three Waikato lakes due to algal bloom.

The District Health Board says Lakes Whangape, Ngaroto and Waikare are dangerous to swim in and should be avoided.

It says going into the water can cause skin and eye irritation, asthma , diarrhoea and vomiting.

The Health Board says if people still choose to go into the water, they should shower and change their clothes as soon as they can.