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Health Advisory: Red Tide Along Texas Gulf Coast

Health Advisory
Health Advisory
October 2, 2023


The Texas Department of State Health Services (DSHS) is notifying the public of a harmful algal bloom, or red tide, caused by Karenia brevis along the Texas Gulf Coast, including the upper coast around Galveston Bay. People should exercise caution and minimize exposure in and around areas with an active bloom.


Karenia brevis is a single-celled organism that lives in the seawater. When it grows, or blooms, it releases a neurotoxin that can kill fish and other sea life and irritate the skin and respiratory tract of people exposed to it. In greater concentrations, it can give the water a pink or red color and can lead to areas of low oxygen in the water.

People and animals can be exposed to a harmful algal bloom by:

  • eating shellfish containing toxins
  • swimming or engaging in other activities in the water
  • breathing in tiny droplets in the air that contain toxins


Adverse Health Effects

Breathing in sea spray or getting water containing toxin on your skin can cause symptoms including:

  • respiratory irritation (coughing, sneezing)
  • shortness of breath
  • throat irritation
  • eye irritation
  • skin irritation
  • asthma attacks

Symptoms usually go away after short-term exposure when you leave the affected area. However, people with an existing respiratory condition such as asthma or chronic lung disease may experience more severe symptoms.

Red tide toxin also can affect the central nervous system of fish and other marine life, which can lead to fish kills. Eating contaminated seafood, including oysters, clams, mussels, and scallops, can cause neurotoxic shellfish poisoning in humans. Symptoms include:

  • abdominal pain
  • nausea and vomiting
  • diarrhea
  • tingling of the mouth, lips, and tongue (later stages can affect pharynx, trunk, and limbs)
  • slurred speech and dizziness


Recommendations for the public

  • Avoid swimming or wading in red tide-infested waters.

  • Do not consume oysters, clams, mussels, and scallops from areas with red tide. Cooking these shellfish does not get rid of the toxin.
  • Fish, shrimp, and crabs can be eaten if caught live because the toxin does not build up in the same way.
  • If fish from red tide areas are caught live and healthy, they are safe to eat if they are filleted, and the guts discarded. Rinse fish with tap or bottled water.
  • Do not consume any fish or shellfish that washed ashore sick or dead or are found floating “belly up” in the water, as this could indicate red tide presence or another potential health issue.
  • Those with chronic respiratory problems should be especially cautious and stay away from locations with red tide.
  • Wash your skin and clothing with soap and fresh water if you have had recent contact with red tide.
  • Keep pets and livestock away from dead sea life and out of the water in areas with red tide.
  • Monitor red tide conditions via the Texas Parks and Wildlife Department:

If an individual is affected by red tide blooms, please consult a health care provider. People may contact the Texas Poison Center Network by calling 1-800-222-1222.

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