Blue-Green Algae: How to Stay Safe by the Water

blue green algae

Hot, dry and still conditions on Lake Champlain and other bodies of fresh water with high concentrations of phosphorous and nitrogen can spur blooms of toxic cyanobacteria, also called blue-green algae.

We talked to Eike Blohm, MD, about the dangers and how to stay safe while enjoying the lake. Blohm is a physician in the Division of Emergency Medicine at UVM Medical Center and a toxicology consultant for the Northern New England Poison Center.

Who is at risk?

Blohm: This type of toxin is not easily absorbed through the skin, so it’s most dangerous when ingested. While adults are not going to drink the water they’re swimming in, kids often do accidentally while diving and playing and dunking their heads. At least with kids, though, you can tell them not to drink the water. At really high risk are dogs. The dog gets hot, and the water tastes good, so they drink it.

Why dogs are especially vulnerable?

Blohm: When a dog swims through a bloom, all the cyanobacteria gets stuck in its fur. Once a dog that’s soaked in cyanobacteria gets out of the water and dries off, the bacteria start to die, and that’s when all the toxin gets released. Before the dog licks it up, make sure you wash and dry him or her off. When I go running with my dog, I don’t run close to the lake because I know my dog will just dart off and drink some of the lake water.

What are the health impacts?

Blohm: There are two groups of toxins in cyanobacteria: neurotoxins can cause numbness or tingling, and hepatic toxins can cause liver failure.

What are the warning signs?

Blohm: People sometimes report getting a sore throat when they’re exposed. That’s probably some of the neurotoxin that they swallowed that is affecting their oropharynx (the part of the throat at the back of the mouth). But, I wouldn’t think, “Oh, I’m not getting a sore throat, therefore this is safe.” In adults, the symptoms of incidental exposure would likely be some nausea, vomiting, abdominal pain and/or diarrhea.

What are the treatment options?

Blohm: There’s no antidote to this, so the only treatment we can provide at the hospital is help with controlling the vomiting or the pain or to prevent you from becoming dehydrated.

How do I enjoy the lake?

Blohm: I like to kayak out of Shelburne Bay and then, once I am in the big lake, I go swimming in the open water. Generally, if you go into the deeper parts of the lake, where you have more turnover of the lake water, it’s probably safe from a toxicity point of view.

How do I stay informed?

Blohm: The Vermont Department of Health has some good resources to identify Cyanobacteria and track Cyanobacteria to find out which areas are affected. Note that all bodies of water are not monitored. Bottom line: stay out of the water if you think cyanobacteria may be present.

If you are concerned that you may have been exposed, call your doctor. If you are a patient of the UVM Medical Center’s Adult Primary Care, Family Medicine or Pediatric Primary Care, call your Primary Care provider any Saturday and Sunday, 8 am – 12 pm, to discuss your weekend health needs. Learn more at

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