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Medically reviewed by Last updated on Jan 1, 2021.

What are other common names?

  • Ascophyllum nodosum
  • Fucus vesiculosis
  • Atlantic Kelp
  • Black Tang
  • Bladder Fucus
  • Bladder Wrack
  • Blasentang
  • Cutweed
  • Fucus
  • Kelp
  • Kelpware
  • Knotted Wrack
  • Laminaire
  • Marine Oak
  • Norwegian Seaweed
  • Ocean Kelp
  • Rockweed
  • Rockwrack
  • Sea Kelp
  • Seaweed
  • Seawrack
  • Tang
  • Varech

What is this product used for?

Bladderwrack is used by some people as a food source. Others use it to help with weight loss or wound healing.

What are the precautions when taking this product?

  • Always check with your doctor before you use a natural product. Some products may not mix well with drugs or other natural products.

  • This product may interfere with some lab tests. Be sure to talk with your doctor about this and all drugs you are taking.

  • Be sure to tell your doctor that you take this product if you are scheduled for surgery or tests.

  • Do not use this product if you are pregnant or plan to become pregnant soon. Use birth control you can trust while taking this product.

  • Do not use this product if you are breastfeeding.

  • Take extra care if you are taking drugs that contain hormones. These are drugs like birth control pills and hormone replacement therapy.

  • Take extra care if you are allergic to iodine.

  • Take extra care if you are taking drugs to thin your blood. These are drugs like warfarin (Coumadin), heparin, or enoxaparin (Lovenox).

  • Take extra care if you are taking drugs to dissolve blood clots. These are drugs like alteplase (Activase), reteplase (Retevase), or streptokinase.

  • Take extra care if you are taking drugs to help with swelling or inflammation. These are drugs like nonsteroidal anti-inflammatory drugs (NSAIDs), aspirin, ibuprofen (Advil), or naproxen (Naprosyn).

  • Take extra care if you are taking drugs for your thyroid. These are drugs like levothyroxine (Synthroid), thyroid desiccated (Armour Thyroid), or liotrix (Thyrolar).

  • Take extra care and check with your doctor if you have:

    • Kidney problems

    • Thyroid problems

    • Bleeding problems

    • Diabetes

What should I watch for?

  • Upset stomach

  • Stomach cramps

  • Shakiness

  • Rash

When do I need to call the doctor?

  • Signs of a very bad reaction. These include wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat. Go to the ER right away.

  • Signs of thyroid problems. These include unexplained weight loss, fast heartbeat, or shakiness.

  • Signs of high blood pressure. These include very bad headaches, nervousness, problems breathing, or nosebleeds.

  • Swollen neck

  • Very bad throwing up

  • Very bad belly pain

  • Very bad loose stools

  • Bruising or bleeding that is not normal

  • Changes in menstrual periods like lots of bleeding, spotting, or bleeding between cycles

Last Reviewed Date


Consumer information use

This information is not specific medical advice and does not replace information you receive from your healthcare provider. Only your healthcare provider has the knowledge and training to provide advice that is right for you. You should not rely on this information in deciding whether or not to use, or accept your healthcare provider’s advice regarding use of, any natural products or similar treatments, therapies, or life-style choices. This information does not endorse any natural products or similar treatments, therapies, or life-style choices as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information. It does NOT include all information about natural products, possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to you. You must talk with your healthcare provider for complete information about your health and treatment options.


Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.