A Red Tide is a type of Harmful Algal Bloom (HAB) caused by a higher-than-normal concentration of the microscopic organism, the dinoflagellate Karenia brevis. This phenomenon releases potent natural toxins that affect marine life and human health. The resulting skin irritation typically manifests as a rash, which is a direct result of contact with these toxins.
Visual Characteristics and Accompanying Symptoms
The Red Tide rash is generally non-specific, often categorized as contact dermatitis or a hive-like reaction. Visually, it presents as patches of redness (erythema) or small, raised bumps. This reaction is usually confined to areas directly exposed to the contaminated water, such as the legs, torso, and uncovered skin.
The rash is accompanied by symptoms like intense itching, burning, and stinging, which typically begin shortly after leaving the water. For most individuals, this temporary rash is mild and resolves quickly, often disappearing within 24 hours once exposure ceases. However, severity varies depending on individual sensitivity and the concentration of toxins in the water.
Understanding the Source of the Skin Irritation
The underlying cause of the Red Tide rash is not the algae itself, but the potent neurotoxins it produces, known as brevetoxins. Karenia brevis releases these toxins into the surrounding seawater, disrupting cellular processes in the skin upon contact. Brevetoxins trigger the release of histamine, a compound that causes localized inflammation, leading directly to the redness, swelling, and itching associated with the rash.
Exposure happens primarily through direct contact with the water while swimming or wading. A second, less common route is contact with aerosolized toxins. When waves crash, they break open algal cells, releasing brevetoxins into the air as fine marine aerosols. While aerosolized exposure is known for causing respiratory irritation, it can also settle on the skin and mucous membranes, contributing to irritation.
Management and When to Seek Medical Attention
The first step in managing a Red Tide rash is to immediately exit the water and thoroughly rinse the affected skin with fresh water. This action washes away remaining toxins and algae from the skin’s surface, limiting further irritation. For relief from itching and burning, effective over-the-counter treatments include applying hydrocortisone cream or taking oral antihistamines.
While most cases are temporary and resolve on their own, certain symptoms warrant professional medical evaluation. Seek medical attention if the rash persists for several days, worsens significantly, or shows signs of a secondary bacterial infection. Signs of infection include increasing pain, severe swelling, warmth, or the presence of pus. It is important to seek immediate care if you experience respiratory issues like persistent coughing, wheezing, or difficulty breathing, as these symptoms indicate a systemic reaction to the inhaled toxins.