When to take Sea Moss
Also known as Irish moss, Chondrus crispus
Sea moss has no best time of day, so take it whenever you will remember it each day. What matters more is how much iodine it adds, so keep your total iodine from all sources under the adult upper limit of 1,100 mcg a day.
Last reviewed October 13, 2026
Timing
| Best time | Any time of day |
|---|---|
| Food | With or without food |
| Fat-soluble | No |
- Any time; consistency matters more than timing.
- The iodine in seaweed varies a lot by species, season and where it grew.
- Red seaweeds like Irish moss usually have less iodine than brown seaweeds like kelp or bladderwrack.
- Count iodine from every source: sea moss, kelp, multivitamins and iodized salt all add up.
Check with your doctor first if…
- Thyroid conditions: too much iodine can cause thyroid problems, and people with autoimmune thyroid disease can react to amounts that are safe for others. Ask your doctor first.
- Thyroid medicine: taking high doses of iodine with antithyroid medicine such as methimazole can add to its effect. Ask your doctor before using sea moss.
- Lithium: people taking lithium may be more sensitive to extra iodine. Ask your doctor first.
- Pregnancy: babies have been born with low thyroid function after their mothers ate a lot of seaweed while pregnant. Ask your doctor before using sea moss.
- Breastfeeding: avoid sea moss unless the product shows its iodine and heavy metal levels are low enough to be safe. Too much seaweed iodine in the mother has slowed thyroid function in breastfed babies.
- Heavy metals: sea moss can carry arsenic, lead, cadmium and mercury from the water it grew in. Choose a product with third-party testing.
- Blends with kelp or bladderwrack: these brown seaweeds hold far more iodine than Irish moss. Check the label for the iodine amount per serving.
Amounts studied
No human trials have tested a sea moss dose. For iodine itself, NIH ODS lists an adult RDA of 150 mcg/day (220 mcg in pregnancy, 290 mcg while breastfeeding) and an adult UL of 1,100 mcg/day. Red seaweeds such as Irish moss hold about 20–200 mcg of iodine per gram dried.
Follow the serving size on your product’s label.
What the research says
| Area | Evidence | Summary |
|---|---|---|
| Iodine intake | Limited | Sea moss contains iodine, which the body uses to make thyroid hormones. No human studies have tested sea moss itself, and no health benefit has been proven.[4] |
Questions
Should I take sea moss in the morning or at night?
There are no studies on sea moss timing. Take it at whatever time you will remember each day. Keeping your daily iodine total in a safe range matters more than the clock.
Can I take sea moss every day?
Iodine from sea moss adds to the iodine you get from salt, food and multivitamins. NIH ODS sets the adult upper limit at 1,100 mcg a day, and long-term intake above it raises the risk of side effects. Because seaweed iodine varies a lot, pick a product that lists iodine per serving.
Can I take sea moss with thyroid medicine?
Ask your doctor first. High iodine taken with antithyroid medicine can add to its effect, and extra iodine can upset thyroid function in people with thyroid disease.
Is sea moss safe while pregnant or breastfeeding?
Ask your doctor before using it. Too much seaweed iodine in the mother has caused low thyroid function in newborns and breastfed babies. LactMed advises avoiding sea moss while breastfeeding unless iodine and heavy metal levels are shown to be low.
Does sea moss have more iodine than kelp?
Usually no. Red seaweeds like Irish moss hold about 20–200 mcg of iodine per gram dried, while brown seaweeds like kelp can hold 2,500–10,000 mcg per gram. That is why sea moss blends with kelp or bladderwrack need a close look at the label.
Plan your whole routine
Add Sea Moss and everything else you take to the planner to see your morning, midday and evening, and what to keep apart.
Open the plannerFrom AT2A
Sources
- Iodine: Fact Sheet for Health Professionals, NIH ODS (accessed October 13, 2026)
- Iodine, Seaweed, and the Thyroid (Smyth, Eur Thyroid J 2021), PubMed Central (accessed October 13, 2026)
- Consequences of excess iodine (Leung & Braverman, Nat Rev Endocrinol 2014), PubMed Central (accessed October 13, 2026)
- Sea Moss (Drugs and Lactation Database, LactMed), NIH National Library of Medicine (accessed October 13, 2026)
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease. It is general information, not medical advice: talk with your doctor or pharmacist before starting a supplement, especially if you are pregnant, breastfeeding, take medicine or have a health condition.