There is interest in using Fucus vesiculosus for a number of purposes, but there isn’t enough reliable information to say whether it might be helpful.

When taken by mouth: Fucus vesiculosus is possibly unsafe. It can contain high concentrations of iodine. Taking large amounts of iodine can cause or worsen some thyroid problems. It might also contain heavy metals, which can cause heavy metal poisoning.

When applied to the skin: Fucus vesiculosus is possibly safe.

Special precautions & warnings:

Pregnancy and breast-feeding: Fucus vesiculosus is possibly unsafe to use while pregnant or breast-feeding because it might contain iodine and heavy metals. Don’t use it.

Surgery: Fucus vesiculosus might slow blood clotting. It might cause extra bleeding during and after surgery. Stop taking Fucus vesiculosus at least 2 weeks before surgery.

Thyroid disorders: Fucus vesiculosus may contain large amounts of iodine. Long-term use or high doses of iodine might make certain thyroid disorders worse. Also, people with autoimmune thyroid disease might be especially sensitive to the harmful effects of iodine.

Moderate

Be cautious with this combination.

Amiodarone (Cordarone)

Fucus vesiculosus and amiodarone both contain iodine. Taking fucus vesiculosus with amiodarone might increase the levels of iodine in the blood. Too much iodine in the blood can cause side effects that affect the thyroid.

Lithium

Fucus vesiculosus can contain large amounts of iodine. Large amounts of iodine can change thyroid function. Lithium can also change thyroid function. Taking Fucus vesiculosus along with lithium might increase the risk of thyroid function changes.

Medications for an overactive thyroid (Antithyroid drugs)

Fucus vesiculosus can contain large amounts of iodine. Iodine can increase or decrease thyroid function. Taking Fucus vesiculosus along with medications for an overactive thyroid might change the effects of these medications.

Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)

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

Thyroid hormone

Fucus vesiculosus contains iodine. Iodine can increase or decrease thyroid function. Taking Fucus vesiculosus along with thyroid hormone medications might increase the effects of these medications.

Minor

Be watchful with this combination.

Medications changed by the liver (Cytochrome P450 2C8 (CYP2C8) substrates)

Some medications are changed and broken down by the liver. Fucus vesiculosus might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates)

Some medications are changed and broken down by the liver. Fucus vesiculosus might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Cytochrome P450 2D6 (CYP2D6) substrates)

Some medications are changed and broken down by the liver. Fucus vesiculosus might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates)

Some medications are changed and broken down by the liver. Fucus vesiculosus might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Herbs and supplements that might slow blood clotting

Fucus vesiculosus 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.

Iodine-containing herbs and supplements

Fucus vesiculosus contains iodine. Taking Fucus vesiculosus with other products that contain iodine might cause iodine levels to go too high. This can cause side effects, such as changes in thyroid function. Examples of supplements that contain iodine include seaweed products, such as dulse and laminaria.

Strontium

Fucus vesiculosus contains alginate. Alginate can reduce the absorption of strontium. Taking Fucus vesiculosus with strontium supplements might reduce the absorption of strontium.

There are no known interactions with foods.

There isn’t enough reliable information to know what an appropriate dose of Fucus vesiculosus might be. Fucus vesiculosus might also be unsafe because it might contain high amounts of iodine and heavy metals. Speak with a healthcare provider before using.