7 Health Benefits of Sea Moss and Side Effects

Sea moss (Irish moss) is a type of red seaweed that may offer health benefits, including improving thyroid function, helping manage diabetes, boosting immune health, and more. Keep in mind that research continues into these potential benefits and there is not yet enough evidence to recommend sea moss for any specific use.

In general, though, seaweeds are rich sources of proteins and minerals. They contain dietary fiber and plant chemicals that may promote good health. Talk with your healthcare provider if you’re interested in the benefits of sea moss and considering its use.

1. Support the Digestive System

Health claims about sea moss include digestive system support. Data from an animal study suggested that sea moss may have some prebiotic effects that can help with digestion. Prebiotics help promote the activity of “good” bacteria that naturally exist in your body.

Still, other studies on sea moss suggest opposite digestive effects. Carrageenan found in sea moss seemed to worsen inflammatory bowel disease (IBD) symptoms, while a carrageenan-free diet may relieve IBD symptoms. Other studies suggest a link between carrageenan and colitis as well.

2. Assist Thyroid Health

Thyroid support is another potential health claim for sea moss. This is because sea moss contains iodine, an essential nutrient your body uses to make thyroid hormones. These hormones help direct various bodily functions, including weight regulation, temperature, and energy levels.

Iodine can affect thyroid function, especially in infants, the developing fetus, and older adults over 65. If you’re using sea moss, a healthcare provider may want to monitor your iodine levels closely and watch for thyroid-related symptoms.

Although food sources—like iodized salt—are preferable over sea moss, some people may benefit from iodine supplements. People with vegan or vegetarian diets are likelier to experience iodine deficiency.

3. Boost the Immune System

Sea moss may support the immune system, though more research is needed. Animal studies of rats and roundworms suggest some benefits for the immune system (the body’s defense system).

One review article, however, reports that carrageenan—a substance in sea moss— can trigger inflammation. Inflammation is typically a defensive immune response against a threat like infection. There are also reports of severe allergic reactions to carrageenan.

4. Fight Cancer

Sea moss is a source of antioxidants, compounds that help to protect health at the cellular level. They protect against free radicals, molecules in the body that are linked to aging and disease.

Some lab studies suggest that the antioxidant properties of sea moss may offer benefits in fighting cancer. But more research is needed to understand the potential antitumor benefits of sea moss.

5. Prevent HPV

Studies that identify the antiviral properties of carrageenan, found in sea moss, suggest it may work to prevent human papillomavirus (HPV) infection. Lab study results on HPV have shown promise.

There have only been a few clinical trials, but they were included in a 2021 review of studies that confirmed the potential HPV prevention benefits and recommended more research. Sea moss may have other antiviral applications, too, whether alone or combined with other substances.

6. Prevent Blood Clots

Researchers have assessed the potential of sea moss in preventing blood clots, as part of an effort to find new alternatives to drugs like heparin and their side effects.

Some studies show promise but more research is needed to identify anticoagulant benefits.

7. Manage Diabetes

Some studies have evaluated the potential benefits of sea moss in managing diabetes, but the information remains limited. Research on polyphenols, for example, has focused on red seaweed but only in the lab. More research is needed to establish any benefits.

Nutrition Information

Ten grams—about 2/3 of a cup—of dried seaweed contains the following nutrients in kilocalories (kcal), grams (g), milligrams (mg), and micrograms (mcg):

• Energy: 4.1 kcal
• Protein: 0.4 g
• Total lipid (fat): 0.05 g
• Carbohydrates: 0.8 g
• Fiber: 0.07 g
• Sugars: 0.06 g
• Calcium: 12.9 mg
• Iron: 0.23 mg
• Magnesium: 7.7 mg
• Phosphorus: 6.0 mg
• Potassium: 16.5 mg
• Sodium: 38.4 mg
• Vitamin C: 1.5 mg
• Choline: 1.2 mg
• Vitamin A: 9.5 mcg
• Vitamin E: 0.096 mg
• Vitamin K: 2.51 mcg

Side Effects

Like many medications and natural products, side effects are possible with sea moss. Generally, the amount of iodine in 3 to 4 g of sea moss daily is likely safe. But if you have higher-than-normal iodine levels, some symptoms may include:

• Burning mouth or throat sensation
• Diarrhea
• Fever
• Nausea or vomiting
• Stomach pain

Aside from iodine-related symptoms, weight loss might be another side effect.

Some severe possible side effects may include:

• Severe allergic reaction: A severe allergic reaction is a serious side effect possible with any medication or food. There are reports of severe allergic reactions to carrageenan, a substance in sea moss. If you’re having a severe allergic reaction, symptoms may include breathing difficulties, itchiness, and rash.
• Iodine poisoning: There is a chance that you might get too much iodine from sea moss. If iodine levels are dangerously high, you may experience a weak heartbeat and coma.
• Metal toxicity: Generally, seaweed may contain toxic metals like lead and mercury, based on where it grew. Symptoms of lead or mercury toxicity may include headaches and changes in thinking.
• Arsenic poisoning: Arsenic poisoning is possible with seaweeds like sea moss. Short-term symptoms may include nausea and diarrhea, but longer-term exposure might result in developing diabetes and cancer.
• IBD flare-up: Carrageenan may trigger an IBD flare-up. Symptoms of a potential IBD flare-up may include stomach pain, diarrhea, and rectal bleeding.

If you’re having a severe allergic reaction or if any of your symptoms feel life-threatening, call 911 and get medical help right away.

Who Should Avoid Sea Moss

A healthcare provider may advise against sea moss if any of the following applies to you:

• Allergies: Avoid sea moss if you have a known allergy to it or its components (ingredients or parts), such as carrageenan. Ask for a complete list of the ingredients if you’re unsure.
• Pregnancy: Sea moss is rich in iodine. Too much iodine may lead to side effects in anyone, including a developing fetus or pregnant people.
• Breastfeeding: High levels of iodine in breast milk may negatively affect nursing infants.
• Adults over age 65: Some older adults may have a greater likelihood of medication side effects.
• Children: Talk with a healthcare provider if you’re considering sea moss for your child.
• IBD: Carrageenan may worsen IBD symptoms. If you have IBD, you may need to avoid sea moss.
• Thyroid conditions: The high iodine amounts in sea moss may affect thyroid function.

How Much Sea Moss Should I Take?

There are very few human clinical trials on sea moss, and there are no formal guidelines on the appropriate dosage of sea moss for any condition.

Generally, 3 to 4 g of dried sea moss every day is likely safe in adults. The specific dose may vary based on the amount of iodine in the specific source of sea moss, other iodine sources in your diet, your age, and your medical condition. Capsules are a common form.

Symptoms of overdoses with sea moss are likely similar to its potential common and serious side effects—but excessive and severe. For example, too much iodine in sea moss might result in a coma. Or, toxic exposures like lead or arsenic may cause complications.

If you suspect you’re experiencing life-threatening side effects, seek immediate medical attention.

Drug Interactions

There is limited information about possible medication interactions with sea moss.

Possible interactions are based on the health claims or potential side effects of sea moss. Some people should not use sea moss, or should use caution if also taking:

• Amiodarone (for irregular heart rhythm): Amiodarone contains significant amounts of iodine. Taking more iodine could cause serious adverse effects.
• Immune support medications: In general, sea moss might affect the immune system. For this reason, caution should be used with other medications—like Humira (adalimumab)—that affect the immune system.
• IBD medications: The carrageenan in sea moss might trigger an IBD flare-up. This means that sea moss might work against IBD medications.
• Thyroid medications: Sea moss is rich in iodine. Sea moss might interfere with thyroid medications, such as Tapazole (methimazole).

It is essential to carefully read a supplement’s ingredients list and nutrition facts panel to know which ingredients and how much of each ingredient is included. Please review this supplement label with your healthcare provider to discuss potential interactions with foods, other supplements, and medications.

Summary

Sea moss is a red seaweed. Some health claims about sea moss include benefits for digestion, thyroid function, and immune health. However, more research is needed to identify and understand the health benefits of sea moss.

What’s more, there are several safety concerns with sea moss. For these reasons, it’s essential to ensure an accurate diagnosis and treatment of any health conditions. Before you take sea moss, you should ask a pharmacist or healthcare provider about the benefits and safety of taking sea moss.