Health Guide


What is it?

Bladderwrack is an herbal medicine that is used for weight loss, low thyroid hormone, atherosclerosis, menstrual problems, and heart disease. It is also used for constipation (difficulty having a bowel movement), upset stomach, high cholesterol, and high thyroid hormone. There are no human scientific studies to verify the use of Bladderwrack at this time.

Other names for Bladderwrack include: Fucus vesiculosus, Kelpware, Black-Tang, Bladder Fucus, Quwecus Marina, Sea Wrack, Sea-Oak, Marine Oak, and Seetang.

Ask your doctor, nurse, or pharmacist if you need more information about this medicine or if any information in this leaflet concerns you.

Before Using:

Tell your doctor if you

  • are taking medicine or are allergic to any medicine (prescription or over-the-counter (OTC) or dietary supplement)
  • are pregnant or plan to become pregnant while using this medicine
  • are breastfeeding
  • have any other health problems, such as high blood pressure or heart or blood vessel disease


Talk with your caregiver about how much Bladderwrack you should take. The amount depends on the strength of the medicine and the reason you are taking Bladderwrack. If you are using this medicine without instructions from your caregiver, follow the directions on the medicine bottle. Do not take more medicine or take it more often than the directions tell you to.

To store this medicine:

Keep all medicine locked up and away from children. Store medicine away from heat and direct light. Do not store your medicine in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down and not work the way it should work. Throw away medicine that is out of date or that you do not need. Never share your medicine with others.

Drug and Food Interactions:

Do not take Bladderwrack without talking to your doctor first if you are taking:

  • Blood thinning medicine (examples: warfarin (Coumadin(R)), clopidogrel (Plavix(R)), aspirin, enoxaparin (Lovenox(R)), dalteparin (Fragmin(R)))


  • Before taking Bladderwrack, tell your doctor if you are pregnant or breastfeeding
  • Do not use Bladderwrack for a long period of time
  • Do not take if you have hyperthyroidism (high thyroid) as it can make your condition worse (3)

Side Effects:

Stop taking your medicine right away and talk to your doctor if you have any of the following side effects. Your medicine may be causing these symptoms which may mean you are allergic to it.

  • Breathing problems or tightness in your throat or chest
  • Chest pain
  • Skin hives, rash, or itchy or swollen skin

Other Side Effects:

You may have the following side effects, but this medicine may also cause other side effects. Tell your doctor if you have side effects that you think are caused by this medicine.

  • Can cause increased (more) thirst and urination
  • Acne (4)
  • Can make existing hyperthyroidism (high thyroid) worse


1. Fetrow CW & Avila JR: Professional's Handbook of Complementary and Alternative Medicines. Springhouse Corporation, Springhouse, PA; 1999.

2. Anon: British Herbal Pharmacopeia. British Herbal Medicine Association, Keighley, England; 1983.

3. McGuffin M, Hobbs C, Upton R et al: American Herbal Product Association's Botanical Safety Handbook. CRC Press, Boca Raton, FL; 1997.

4. Harrell BL & Rudolph AH: Kelp diet: a cause of acneiform eruption. Arch Dermatol 1976; 112: 560.

5. Kowalak JF & Mills EJ (Eds): Professional Guide to Complementary & Alternative Therapies. Springhouse Corp., Bethlehem Pike, PA; 2001.

Last Updated: 7/4/2018
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites.

All rights reserved