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Can Red Tide Make You Sick?

Can Red Tide Make You Sick?

With SMH Pulmonary Disease Specialist Kirk Voelker, MD

Red tide is on the rise in Sarasota County, leaving dead fish and marine life littering beaches and carrying foul-smelling breezes up to a mile inland. The return of the Karenia brevis red tide has certainly put a damper on summer plans for beach days and boating. But what exactly are red tide's health effects?

For beachgoers, coastal residents and others exposed to Karenia brevis (K. brevis) algal blooms, the red tide’s toxins can irritate the eyes, nose, throat and respiratory system. Symptoms can be pronounced in those with underlying chronic respiratory conditions, including asthma, emphysema and COPD.

Should we skip the beach during red-tide blooms?

“If you're a healthy person with no respiratory problems, red tide irritation may make you cough, but it won't cause permanent harm,” explained SMH Pulmonary Disease specialist Kirk Voelker, MD. “It's an irritant just like tree pollen or something like that.”

But he cautioned that people with asthma, emphysema or chronic bronchitis should avoid areas where red tide levels are high.

What Is Red Tide?


What we commonly know as “red tide” is referred to by ocean scientists as a “harmful algal bloom,” or HAB. HABs can, and do, happen all along the coastal U.S. But on Florida’s Gulf Coast, red tide blooms occur each summer. These come from a particular, microscopic saltwater algae known as Karenia brevis (K. brevis) or “Florida red tides,” as they can give the water a reddish tint.

At its worst, severe red tide causes major fish kills, sickens marine mammals and taints shellfish — as it did along the Suncoast in 2018. Onshore effects include foul-smelling air and causing irritation to the eyes, nose and lungs for those near impacted waterways.

“If you have respiratory problems — specifically asthma or emphysema which are actually diseases of inflammation — then red tide can trigger your respiratory inflammatory response,” Dr. Voelker added.

If the red tide bloom lasts for weeks, talk to your doctor. You may need to start a steroid medication to combat your symptoms, Dr. Voelker said. If you’re already using inhaled oral steroids to treat chronic respiratory issues, you may need to have your dosage increased to keep symptoms under control.

Is it safe to swim during a red tide bloom?

Swimming in the ocean during low-level or moderate red tide is typically safe for most people, but it won’t necessarily be a pleasant experience. Be careful if you’re swimming in red tide waters and have open wounds; flush the wound with fresh water as soon as you can. 

If dead fish are present, stay out of the water.

Is it safe to eat shellfish harvested in red tide-affected waters?

No. Eating red tide-contaminated shellfish can make you sick — possibly really sick — with brevetoxicity, also known as neurotoxic shellfish poisoning. Know where your seafood comes from. Do not harvest or eat shellfish from waterways where there’s a red tide bloom. Only eat shellfish sourced from clean water or bought in a trusted seafood market, grocery store or restaurant. Click here to learn more.

Steps to Reduce Red Tide Symptoms

If red tide’s got you blue, here’s what you can do.

  • Keep track. Scientists can’t yet predict exactly when or where a red tide bloom will occur, but once it’s identified, they can track its movements and monitor its intensity. Keep an eye on local red-tide trackers to see whether it’s a beach day or an inside day. To check red tide conditions at your favorite beach, use Mote Marine's helpful tool, along with the recommended tracking resources below.

  • Stay inside. If you live in a coastal area, try to limit your time outside. Shut your windows and doors, and turn on the air conditioning. Make sure that your AC filter is changed regularly and consider switching to a HEPA filter, Dr. Voelker suggested.

  • Take your meds. People with chronic respiratory conditions should be diligent about taking their medications during a red tide event. For those without chronic breathing problems, over-the-counter antihistamines can help ease red-tide symptoms like coughing, itchy throat and irritated eyes.

If your symptoms worsen beyond what you consider normal for your condition, seek medical care at an Urgent Care Center.

Protect Pets from Red Tide


Pets and livestock are not immune to red tide toxins and can also be affected by blooms.

Coastal residents should keep pets indoors when possible during algal blooms to spare them the respiratory irritation.

When visiting the beach or impacted waterways, keep pets away from dead fish and sea foam, both of which can be harmful. Be sure to rinse your pet with clean water as soon as possible.

Red Tide Tracking & Monitoring 

These resources can help you and others keep track of red tide in your area.



Written by Sarasota Memorial Copywriter Philip Lederer, MA. As a local journalist and an in-house Sarasota Memorial wordsmith, Lederer crafts a variety of external communications for the healthcare system. He earned his Master’s degree in Public Administration and Political Philosophy from Morehead State University, Ky.


Posted: Jul 13, 2021,
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Author: Ann Key