Blue-green algae

Blue-green algae

Blue-green algae are bacteria (cyanobacteria). Blue-green algae, like real algae, develop mainly when there is a high supply of nutrients during periods of good weather or in midsummer. Depending on the direction of the wind, they are driven together on the surface of the water on lakeshores, where they form streaks and flakes. Often large algal carpets are also visible.

  • What is the route of infection and what symptoms do I get?

    Some species of blue-green algae can form toxins. These can cause allergic reactions, nausea, fever, vomiting and diarrhoea in bathers through skin contact or ingestion. If these complaints occur after bathing, please consult a doctor! Dogs are also very sensitive to blue-green algae. If you notice strong algae formation, you should not let your pet go into the water in this area.

  • How can I protect myself?

    • If you cannot see your feet in knee-deep water, you should not bathe.
    • As a general rule, do not swallow or swallow as little water as possible from bathing water (pay particular attention to this with children).
    • In case of contact with water with a high algae content, wash off immediately with soap or shower off.
    • Consult a doctor if you have symptoms (diarrhoea, nausea, vomiting, fever or allergic reactions).
  • What does blue-green algae look like?

    Blue-green algae are greenish, elongated formations that can be found a few centimetres below the water surface. Contrary to what their name suggests, they make public bathing places shimmer greenish. If the blue-green algae infestation is quite severe, the entire body of water becomes discoloured.


  • Can you still go into water?

    Bathing bans should be observed at all costs, even if contact with blue-green algae does not pose a danger to people's lives. There is no way to protect yourself from blue-green algae - except to avoid contact with them.

  • What happens on contact with blue-green algae?

    Blue-green algae are toxic to humans and animals. Contact with blue-green algae can lead to skin irritations and allergies. It is particularly unpleasant when people swallow water contaminated with blue-green algae. This can lead to nausea and vomiting. Respiratory problems, circulatory problems, headaches, earaches, aching limbs and conjunctivitis can also be triggered by blue-green algae. If possible, do not share bed linen, towels and other items such as crockery with other people. Ensure good hand hygiene.

    Frequently touched surfaces such as bedside tables, smartphones or tablets should be cleaned carefully and at least once a day.

    • Bathroom and toilet surfaces should be cleaned after each use.
    • Avoid direct contact with pets to prevent human-to-pet transmission.
    • If your health deteriorates, inform the doctor treating you immediately.