Carrageenan is made from parts of various red seaweeds in the Rhodophyceae family. It's commonly used to thicken foods, but it has no nutritional value.

Carrageenan has been added to processed foods since the 1950s. Carrageenan might also help fight infections.

People use carrageenan for cough, common cold, and other conditions, but there is no good scientific evidence to support any uses.
When taken by mouth: Carrageenan is commonly consumed in foods. A broken down form called poligeenan is possibly unsafe. It might damage the colon and cause bleeding and cancer. But this risk hasn't been shown in humans. Also, carrageenan products found in the US and Europe can only contain a very small amount of this broken down form.

When sprayed into the nose: Carrageenan is possibly safe for most people when used for up to 7 days.

When applied to the skin: There isn't enough reliable information to know if carrageenan is safe. It might cause side effects such as discomfort.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Carrageenan is commonly consumed in foods. There isn't enough reliable information to know if it's safe in the larger amounts used as medicine. Stay on the safe side and stick to food amounts.

Bleeding disorders: Carrageenan might slow blood clotting and increase bleeding. Carrageenan might make bleeding disorders worse.

Surgery: Carrageenan might slow blood clotting in some people. Carrageenan might increase the risk for bleeding and interfere with blood pressure control during surgical procedures. Stop using carrageenan at least 2 weeks before a scheduled surgery.

Ulcerative colitis: Carrageenan might increase the risk of relapse in people with ulcerative colitis who are in remission and are on a carrageenan-free diet.


NatMed Pro rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
Likely effective Effectiveness definitions
Possibly effective Effectiveness definitions
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Possibly ineffective Effectiveness definitions
  • A sexually transmitted infection that can lead to genital warts or cancer (human papillomavirus or HPV). Applying a carrageen gel before intercourse does not reduce the risk of anal HPV in males who have sex with males.
There is interest in using carrageen for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.
Insufficient evidence Effectiveness definitions

Dosing & administration

Carrageenan is commonly added to processed foods.

As medicine, there isn't enough reliable information to know what an appropriate dose of carrageenan might be. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult a healthcare professional before using.

Interactions with pharmaceuticals

Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)

Interaction Rating=Moderate Be cautious with this combination.

Carrageenan might slow blood clotting. Taking carrageenan along with medications that also slow blood clotting might increase the risk of bruising and bleeding.

Interactions with herbs & supplements

Herbs and supplements that might slow blood clotting: Carrageenan might slow blood clotting and increase the risk of bleeding. Taking it with other supplements with similar effects might increase the risk of bleeding in some people. Examples of supplements with this effect include garlic, ginger, ginkgo, nattokinase, and Panax ginseng.

Interactions with foods

There are no known interactions with foods.
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