Red tide FAQs

Red tide cells
Karenia brevis (red tide) cells - Mote Marine | Submitted

What is red tide?

A red tide is a higher-than-normal concentration of a microscopic alga (plantlike organism). In the Gulf of Mexico, it is Karenia brevis, often abbreviated as K. brevis. At high concentrations, the organisms may discolor the water, sometimes red, light or dark green, brown or the water may appear clear.

What causes red tide?

A red tide bloom develops when biology (the organisms), chemistry (natural or man-made nutrients for growth) and physics (tides, winds, currents) work to produce the algal bloom. No one factor causes the development of a red tide bloom.

Where can I check the status of red tide at my local beach?

Florida Fish and Wildlife Conservation Commission (FWC) Red Tide Current Status: and Mote Marine Laboratory:

Are red tides new?

No. Red tides were documented in the Gulf of Mexico as far back as the 1700s and along Florida’s Gulf Coast since the 1840s. While red tides and other algal blooms occur worldwide, K. brevis is found almost exclusively in the Gulf of Mexico but has been found on the east coast of Florida and off the coast of North Carolina.

How long does a red tide last?

Red tide blooms can last days, weeks or months and can also change daily due to wind conditions and ocean currents.

Is it safe to swim in water affected by red tide?

While people swim in red tide, some individuals may experience skin irritation and burning eyes. If your skin is easily irritated, avoid red tide water. If you experience irritation, get out of the ocean and thoroughly wash off with fresh water.

Can red tide affect me when I am not on the beach?

People in coastal areas near the shoreline may experience varying degrees of eye, nose, and throat irritation. When a person leaves an area with red tide, symptoms usually go away. If symptoms persist, please seek medical attention.

Are there people who are more sensitive to the toxins caused by red tide?

People with respiratory problems (like asthma, emphysema or bronchitis) should avoid red tide areas, especially when winds are blowing on shore. If you go to the beach and have one of these conditions, you should be very cautious. If you have symptoms, leave the beach and seek air conditioning (A/C). If symptoms persist, seek medical attention.

What can I do to lessen the effects of red tide?

People usually get relief from respiratory symptoms by being in air-conditioned spaces. This is also true when driving: keep your car windows up and the A/C or heat on. For people without asthma or any other chronic respiratory problems, over-the-counter antihistamines may relieve symptoms. People with chronic lung ailments should be especially vigilant about taking prescribed medications daily. Always seek medical care if your symptoms worsen.

Can red tide affect pets?

Just like people, pets may be affected by red tide. If you live close to the beach, consider bringing outdoor pets inside during a bloom to prevent respiratory irritation. If you are at the beach with your pets, do not allow them to play with dead fish or foam that may accumulate on the beach during or after a red tide. If your pet swims in the red tide, wash it off with fresh water as soon as possible.

Is seafood in the area safe to eat?

Clams and oysters (mollusks) can contain red tide toxins that cause neurotoxic shellfish poisoning. Check local harvesting status before collecting at Finfish caught live and healthy can be eaten if filleted and rinsed thoroughly. The edible meat of crabs, shrimp, and lobsters (shellfish) can be eaten (do not eat the tomalley—the green digestive gland—of shellfish). Do not eat distressed or animals found dead under any circumstances.

Source: Florida Department of Health