Bladderwrack

Add 1 teaspoon (5 mL) of dried bladderwrack to boiling water and allow it to simmer for 10–15 minutes.

Though generally recognized as safe, bladderwrack may have some unwanted side effects.

Applying bladderwrack to the skin is likely safe. However, avoid applying it to open wounds and cuts, and discontinue use if you experience any adverse reactions, such as a skin rash.

Like other edible seaweeds, bladderwrack is safe to eat when consumed in small amounts. However, it contains high levels of iodine, salt, and heavy metals, which can pose health risks, especially when taken in supplement form (31Trusted Source).

In one case, a 60-year-old man experienced hyperthyroidism after taking bladderwrack supplements along with lithium, a medication to treat bipolar disorder. After discontinuing bladderwrack, his thyroid levels returned to normal (32Trusted Source).

Along with those with thyroid disorders, bladderwrack may be unsafe for women who are pregnant or breastfeeding. Until further research is available, avoid taking bladderwrack supplements and consult your healthcare provider before eating or drinking it.

Moreover, bladderwrack may interfere with other medications and herbal products, such as blood thinners (e.g., heparin, warfarin), antiarrhythmic medications (e.g., amiodarone), thyroid medications, St. John’s Wort, ginkgo biloba, and valerian root (32Trusted Source, 33Trusted Source, 34Trusted Source).

Be sure to consult your healthcare provider before taking bladderwrack.