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Iodine is an essential mineral that plays an important role in maintaining the health and function of your thyroid gland.
The thyroid gland is a butterfly-shaped organ located in your neck that produces specific hormones that help regulate growth and metabolism (1).
Iodine functions as a building block of the two main thyroid hormones — triiodothyronine (T3) and thyroxine (T4) (2).
If your iodine intake is too low, you can end up with low levels of thyroid hormone in your blood. This can lead to symptoms like swelling of the thyroid gland (also known as goiter), fatigue, dry skin, hair loss, difficulty regulating body temperature, and weight gain (1).
Iodine is naturally found in a variety of foods, such as seafood, dairy products, eggs, and seaweed. It may also be found in grains and some fruits and vegetables. However, the exact amount depends primarily on the iodine levels of the soil in which the crop was grown (1).
Given the variability in iodine levels in many plant-based foods, some countries have iodine-fortified foods available, such as iodized salt, to prevent deficiencies.
Even so, certain groups of people are at an increased risk of iodine deficiency, including (1):
- people who are pregnant
- people living in places where the soil is iodine-depleted
- people following strict vegan and vegetarian diets
- people who avoid or have limited access to iodized salt
If you have difficulty getting enough iodine in your diet, a healthcare professional may recommend that you take an iodine supplement.
A quick look at the best iodine supplements
- Best all-around: Pure Encapsulations Iodine
- Best rigorously tested: Thorne Iodine & Tyrosine
- Best iodine with calcium: Standard Process Prolamine Iodine
- Best high dose: Life Extension Sea-Iodine
- Best ultra high dose: Swanson Triple Iodine Complex
- Best for thyroid support: Designs for Health Iodine Synergy
- Best overall seaweed-derived: Peak Performance Whole Food Iodine
- Best budget-friendly seaweed-derived: NOW Kelp
- Best liquid form: Mary Ruth’s Organics Liquid Iodine Drops
- Best eco-friendly: future kind+ Liquid Iodine Drops
- Best all-around prenatal with iodine: EU Natural GLOW
- Best gummy prenatal with iodine: Smarty Pants
- Best subscription prenatal with iodine: Ritual Essential Prenatal
How we chose the best iodine supplements
The supplements on this list were chosen according to:
- Vetting. All the products included have been vetted to ensure that they meet Healthline’s medical and business standards.
- Ingredient quality and effectiveness. Quality and effectiveness of ingredients are extremely important in dietary supplementation. Most products on this list include forms of iodine with higher rates of bioavailability and absorption, such as potassium iodide and pure iodine found in whole food sources.
- Price. We considered overall cost. The cost per serving ranges from $0.04–$1.16 to accommodate a wide variety of preferences and budgets.
- Manufacturing and testing standards. The Food and Drug Administration (FDA) does not quality-test or regulate supplements as closely as medications. Thus, we made sure to include products that are made in facilities that adhere to current good manufacturing practices (CGMPs) and/or have been approved by independent third-party organizations such as NSF International, United States Pharmacopeia (USP), or ConsumerLab.
How to choose an iodine supplement
When choosing a nutritional supplement, you’ll want to consider a variety of factors, including the price, quality, ingredient content, and dosage.
Certain brands are more expensive than others, but price isn’t necessarily a good indicator of quality.
In certain countries, including the United States, nutritional supplements are not as tightly regulated as medications.
Thus, the safest option is to stick with supplements that are produced by reputable companies in CGMP-compliant facilities that maintain high manufacturing standards and routinely test their products for purity and potency.
Furthermore, it’s a good idea to choose supplements approved by third-party organizations such as NSF, USP, and ConsumerLab.
One of the best indicators of product quality is a certificate of analysis (COA), which is awarded to companies whose products have been vetted by third-party testing groups to help ensure safety and quality.
You’ll also want to inspect the ingredient label. If you’re looking to avoid any specific ingredients, such as added sugar, animal products, artificial sweeteners, or allergens, always check the ingredient list before purchasing.
Finally, it’s important to evaluate the dosage. Supplements often contain more than the recommended daily amount of a nutrient, so you want to be careful that you don’t accidentally consume too much.
Conversely, if a healthcare professional recommends that you take a high dose, make sure to choose one that provides an adequate amount to meet your needs.
Healthline’s picks of the best iodine supplements
A note on price
General price ranges with dollar signs ($–$$$) are indicated below. One dollar sign means the product is rather affordable, whereas three dollar signs indicate a higher price range.
Generally, prices range from $0.04–$1.16 per serving, or $3.60–$34.99 per container, though this may vary depending on where you shop and whether you enroll in a subscription.
Note that serving sizes vary by product.
Pricing guide
- $= under $0.25 per serving
- $$= $0.25–$0.50 per serving
- $$$= over $0.50 per serving
Best all-around
Pure Encapsulations Iodine
- Price:$
- Form: capsules
- Serving size: 1 capsule
- Dose: 225 mcg, or 150% of the Daily Value (DV)
Each of these Pure Encapsulations iodine capsules provides 225 mcg of iodine, or 150% of the recommended DV, in a highly absorbable form called potassium iodide.
When it comes to quality, Pure Encapsulations is an industry leader. All of their raw materials and finished products are third-party tested for purity and potency, so you can rest assured that you’re always getting what you’ve paid for.
These capsules are vegan; free of mostmajor allergens, including gluten, wheat, egg, and nuts; and free of artificial colors and sweeteners.
Pros
- low cost
- convenient single-capsule serving size
- third-party tested
- made in a CGMP-compliant facility
- vegan
- free of artificial colors and sweeteners
Most rigorously tested
Thorne Iodine & Tyrosine
- Price:$$
- Form: capsules
- Serving size: 1 capsule
- Dose: 225 mcg, or 150% of the DV
Thorne is a reputable brand known for producing a variety of high quality, allergy-friendly nutritional supplements.
Its iodine supplement is designed to support thyroid health using a combination of 225 mcg of potassium iodide, or 150% of the DV, and 500 mg oftyrosine— an amino acid your body uses to produce thyroid hormones (2).
This supplement is free of sugar, artificial sweeteners, and major allergens like gluten, wheat, tree nuts, dairy, and soy.
All of Thorne’s nutritional supplements are tested for purity and potency, and their manufacturing facilities are certified by multiple regulatory agencies, including NSF International and the Therapeutic Goods Administration.
Pros
- Convenient single-capsule serving size
- third-party tested
- made in a CGMP-compliant facility
- free of major allergens
- free of artificial sweeteners
Best iodine with calcium
Standard Process Prolamine Iodine
- Price:$
- Form: tablets
- Serving size: 1 tablet
- Dose: 600 mcg, or 400% of the DV
Standard Process Prolamine Iodine provides 600 mcg of iodine, or 400% of the DV, and 30 mg of calcium in each capsule.
The iodine comes from a combination of kelp and Standard Process’s proprietary potassium iodide and cornmeal whole food complex. It’s vegan andgluten-free.
Standard Process prides itself on its high manufacturing standards. Each of its supplements is tested for purity and potency an average of six times before being sent to market.
Keep in mind that this supplement contains about 3% of the DV of calcium. This is not harmful for most people, but if you’re already taking a calcium supplement, you may be at a slight risk of consuming too much.
Additionally, if you need a calcium supplement because of a deficiency, this product does not provide enough, and you may need a separate calcium supplement.
Calcium supplements may interfere with the absorption of certain prescription thyroid medications if they’re consumed at the same time. If you are taking a thyroid medication, consult a healthcare professional before adding this supplement to your routine.
Pros
- low cost
- convenient single-capsule serving size
- vegan
Best high dose iodine supplement
Life Extension Sea-Iodine
- Price:$
- Form: capsules
- Serving size: 1 capsule
- Dose: 1,000 mcg, or 667% of the DV
Some people may benefit from supplementing with high doses of iodine for a short period of time. Each of Life Extension’s Sea-Iodine capsules provides 1,000 mcg of iodine, or 667% of the DV, sourced from a combination of kelp and potassium iodide.
All of Life Extension’s ingredients are meticulously studied, and their final products are manufactured in facilities certified by NSF International, so you know you’re always getting a high quality supplement.
For the sake of transparency, Life Extension provides a COA for every batch of supplements they produce, so you can see exactly what’s in the product you’ve purchased.
Keep in mind that you should not attempt to take exceptionally high doses of iodine without guidance from a qualified healthcare professional.
Pros
- low cost
- made in a CGMP-compliant facility
- COA available for every batch of supplements produced
Best ultra high dose iodine supplement
Swanson Triple Iodine Complex
- Price:$
- Form: capsules
- Serving size: 1 capsule
- Dose: 12,500 mcg, or 8,333% of the DV
Swanson’s Triple Iodine Complex supplement provides a very high dose of iodine — 12,500 mcg, or 8,333% of the DV — in the form of potassium iodide, sodium iodide, and kelp-derived iodine.
All of Swanson’s supplements are tested for purity and potency in-house, as well as by third-party laboratories. What’s more, all of their manufacturing facilities are certified by the FDA.
Pros
- low cost
- vegetarian
- third-party tested
- made in a CGMP-compliant facility
- convenient single-capsule serving size
Best for thyroid support
Designs for Health Iodine Synergy
- Price:$
- Form: capsules
- Serving size: 1 capsule
- Dose: 10,000 mcg, or 6,667% of the DV
Designs for Health’s Iodine Synergy supplement contains 10,000 mcg of iodine, or 6,667% of the DV, in the form of potassium iodide, plus 40 mcg ofselenium, a nutrient that functions as an antioxidant and aids thyroid hormone metabolism (3).
It is vegan and free of most major allergens, including dairy, soy, and gluten. It also comes in a glass bottle for easy recycling.
Designs for Health is a reputable brand that maintains stringent quality standards during each step of the manufacturing process. All their products are tested for purity, potency, and safety, and all their production facilities are FDA-certified.
Pros
- low cost
- vegan
- made in a CGMP-compliant facility
- convenient single-capsule serving size
- also contains selenium for thyroid support
Best seaweed-derived
Peak Performance Whole Food Kelp Iodine
- Price:$$
- Form: capsules
- Serving size: 1 capsule
- Dose: 150 mcg, or 100% of the DV
Seaweed is one of the richest natural, plant-based sources of iodine. This iodine supplement provides 150 mcg of iodine, or 100% of the DV, sourced exclusively fromorganickelp. If you prefer supplements sourced from whole food ingredients, this may be a good option.
It’s vegan and free of most major allergens, including tree nuts, fish, shellfish, eggs, wheat, and gluten.
No additives, fillers, or sweeteners are added to the supplement, and all of the company’s products are third-party tested for purity. However, when we reached out, they did not disclose the name of the testing organization for proprietary reasons.
Pros
- vegan
- third-party tested
- made in a CGMP-compliant facility
- convenient single-capsule serving size
Best affordable seaweed-derived
NOW Kelp
- Price:$
- Form: tablets
- Serving size: 1 tablet
- Dose: 150 mcg, or 100% of the DV
NOW is a popular supplement brand that boasts an affordable price point without compromising quality.
Their vegan-friendly kelp supplement contains 150 mcg of iodine, or 100% of the DV, sourced exclusively from whole organickelp.
All of NOW’s manufacturing facilities are FDA-approved, and all of their supplement ingredients undergo rigorous testing for purity and potency.
Pros
- low cost
- made in a CGMP-compliant facility
- convenient single-capsule serving size
Best liquid form
Mary Ruth’s Organics Liquid Iodine Drops
- Price: $
- Form: liquid drops
- Serving size: 2 drops
- Dose: 250 mcg, or 167% of the DV
Mary Ruth’s Organics has become a popular supplement company among families because of the impressive list of products they offer for a wide age range, from infants to women and men over 40.
Their liquid drops are a very affordable option, at just $0.05 per serving, and provide 250 mcg of potassium iodide per serving. This product is vegan-friendly, non-GMO, and certified USDA organic.
Mary Ruth’s Organics claims to treat customers like family and has a full refund policy that doesn’t require a product return.
Pros
- low cost
- vegan
- third-party tested
- made in a CGMP-compliant facility
- certified USDA organic
Best eco-conscious
future kind+ Liquid Iodine Drops
- Price: $$
- Form: liquid drops
- Serving size: 10 drops
- Dose: 150 mcg, or 100% of the DV
This product comes from a supplement company founded by two Australian nutritionists. Their website states that their products are third-party tested and evidence-based and use only 100% cruelty-free vegan ingredients.
These liquid iodine drops provide 150 mcg of iodine, costing approximately $0.42 per 10-drop serving. There are also subscription options available, which can save you 5–20% per bottle.
This product is a great option for the eco-conscious consumer, as future kind+ is B Corp Certified, using recyclable packing and carbon-neutral shipping.
Pros
- vegan
- third-party tested
- made in a CGMP-compliant facility
- eco-conscious B Corp Certified company
Best all-around prenatal supplement with iodine
Eu Natural GLOW Prenatal
- Price:$$$
- Form: capsules
- Serving size: 2 capsules
- Dose: 150 mcg, or 68% of the DV during pregnancy (100% of the standard DV)
Iodine is a very important nutrient for sustaining a healthy pregnancy, but many prenatal supplements do not contain iodine at all.
Each serving of GLOW prenatal capsules provides 150 mcg of iodine, or 68% of the DV during pregnancy, alongside more than 20 other nutrients that support healthy prenatal development.
The brand claims that it always uses the highest quality, most absorbable nutrient forms and that all of its products are third-party tested for purity and potency.
The U.S. Dietary Guidelines recommend that people who are pregnant consume at least 220 mcg of iodine per day (1).
Thus, if you choose GLOW as your prenatal supplement, it’s still important to make sure you’re includingiodine-rich foodsin your diet to meet your daily needs.
Supplements are designed to fill nutrient gaps, but a balanced diet is still an integral part of a healthy pregnancy.
Pros
- vegetarian
- third-party tested
- made in a CGMP-compliant facility
Best gummy prenatal supplement with iodine
Smarty Pants Prenatal Gummies
- Price:$$$
- Form: gummies
- Serving size: 4 gummies
- Dose: 290 mcg, or 132% of the DV during pregnancy
Note: Though this product receives a $$$ price rating based on its list price, some retailers may offer significant discounts.
Smarty Pants prenatalgummiesare a great option if you’re pregnant and have difficulty tolerating capsules.
All Smarty Pants products are third-party tested for purity, so you don’t have to worry about them containing any contaminants or potentially harmful ingredients that are not listed on the label.
Smarty Pants does not disclose its third-party laboratory for proprietary reasons, but you can access certificates of compliance for each supplement on the company’s website.
You get 290 mcg of iodine, or 132% of the DV during pregnancy, in each 4-gummy serving. The same serving also meets 100% of the DV for lactation postpartum (290 mg), so you could continue this same supplement after giving birth.
The gummies are sweetened with a combination of cane sugar and tapioca syrup, but they contain only 6 grams ofadded sugarper serving.
They’re free of artificial sweeteners and naturally colored with fruit and vegetable juices. The company also offers an organic version for anyone who prefers organic supplements.
Pros
- gummy form may be easier or better tolerated for some
- free of artificial flavors and colors
- third-party tested
- made in a CGMP-compliant facility
Best subscription prenatal supplement with iodine
Ritual Essential Prenatal
- Price: $$$
- Form: capsules
- Serving size: 2 capsules
- Dose: 150 mcg, or 68% of the DV during pregnancy
Ritual is a subscription-based supplement company known to have rigorous standards for ingredient quality, effectiveness, and traceability.
Their essential prenatal supplement provides 150 mcg of potassium iodide as well as methylated folate, an active form of folic acid, another essential nutrient for healthy pregnancies.
While they claim to have third-party testing done to ensure supplements don’t contain harmful levels of heavy metals or microbes, they also perform in-house testing for potency, purity, and safety standards.
Notably, Ritual has registered dietitians and biomedical experts on their scientific leadership team and advisory board.
Pros
- vegan
- free of major allergens
- traceable ingredients
- third-party tested for heavy metals and microbes
- made in CGMP-compliant facility
Comparing iodine supplements
PriceFormProsConsiderationsPure Encapsulations Iodine$capsule• low cost• single-capsule serving size
• third-party tested
• made in a CGMP-compliant facility
• vegan
• free of artificial colors and sweeteners not ideal for those who prefer a form other than capsulesThorne Iodine & Tyrosine$$capsule• single-capsule serving size
• third-party tested
• made in a CGMP-compliant facility
• free of major allergens
• free of artificial sweeteners • moderate cost
• not ideal for those who prefer a form other than capsules
• also contains tyrosine to support healthy adrenal functionStandard Process Prolamine Iodine$capsule• low cost
• single-capsule serving size
• vegan• not third-party tested
• not ideal for those who prefer a form other than capsules
• also contains calcium, which may interfere with thyroid medicationsLife Extension Sea-Iodine$capsule• low cost
• vegetarian
• made in a CGMP-compliant facility
• COA available for every batch of supplements produced• not ideal for those who prefer a form other than capsules
• high dose (>200% of the DV) that may not be appropriate for long-term useSwanson Triple Iodine Complex$capsule• low cost
• vegetarian
• third-party tested
• made in a CGMP-compliant facility
• single-capsule serving size• not ideal for those who prefer a form other than capsules
• very high dose (>1,000% of the DV) that may not be appropriate for long-term useDesigns for Health Iodine Synergy$capsule• low cost
• vegan
• made in a CGMP-compliant facility
• single-capsule serving size • not third-party tested
• not ideal for those who prefer a form other than capsules
• very high dose (>1,000% of the DV) that may not be appropriate for long-term use
• also contains selenium for thyroid supportPeak Performance Whole Food Iodine$$capsule• vegan
• third-party tested
• made in a CGMP-compliant facility
• single-capsule serving size• moderate cost
• not ideal for those who prefer a form other than capsulesNOW Kelp$capsule• low cost
• single-capsule serving sizenot ideal for those who prefer a form other than capsulesMary Ruth’s Organic Liquid Iodine Drops$liquid drops• low cost
• vegan, third-party tested
• made in a CGMP-compliant facility
• certified USDA organic liquid not as portable or convenient as other formsFuture Kind+ Iodine Drops$$liquid drops• vegan
• third-party tested
• made in a CGMP-compliant facility
• eco-conscious B Corp Certified company • moderate cost
• liquid not as portable or convenient as other forms Eu Natural GLOW Prenatal$$$capsule• vegetarian
• third-party tested
• made in a CGMP-compliant facility • expensive
• not ideal for those who prefer a form other than capsulesSmarty Pants Prenatal Gummies $$$gummy• gummy form may be easier or better tolerated for some
• free of artificial flavors and colors
• third-party tested
• made in a CGMP-compliant facility • expensive
• contains added sugarRitual Essential Prenatal$$$capsule• vegan
• free of major allergens
• traceable ingredients
• third-party tested
• made in CGMP-compliant facility • expensive
• not ideal for those who prefer a form other than capsules
Useful supplement shopping guides
- How to Choose High Quality Vitamins and Supplements
- How to Read Supplement Labels Like a Pro
Safety precautions
It’s important to consult a healthcare professional prior to taking an iodine supplement, as getting too much can lead to very serious side effects.
Overconsuming iodine can lead to symptoms similar to those of iodine deficiency, such as enlarged thyroid, fatigue, and weight gain. More serious side effects include inflammation of the thyroid gland and thyroid cancer (1).
Acute iodine toxicity is rare but can occur if high doses are taken without medical supervision. Symptoms of iodine toxicity include nausea, vomiting, fever, diarrhea, a weakened heartbeat, and a burning sensation in your throat and mouth (1).
The DV for iodine for healthy adults ages 18 and up is 150 mcg. If you are pregnant or nursing, the daily dose increases to 220 mcg and 290 mcg, respectively (1).
Iodine may negatively interact with some medications, such as diuretics, certain types of blood-pressure-lowering medications, and medications used to treat hyperthyroidism (1).
Most serious adverse reactions occur when iodine intakes exceed 1,100 mcg per day for an extended period of time. Therefore, you should not attempt to take doses higher than the recommended daily amount without medical supervision (1).
When to see a doctor
If you take hyperthyroidism medications, ACE inhibitors, or potassium-sparing diuretics, you should consult your doctor before adding an iodine supplement to your routine since there is potential for drug-nutrient interaction (1).
If you suspect you have low iodine or an iodine deficiency, you can ask a healthcare professional about having your iodine level checked and thyroid function tests done in order to determine an optimal supplemental dose of iodine for you.
Frequently asked questions
Is it OK to take iodine supplements?
Generally, yes, it is safe to take supplements containing iodine. However, many dietary supplements provide more than 100% of the DV of iodine, and it’s important to avoid high doses unless directed otherwise by a healthcare professional (1).
What are iodine supplements good for?
Iodine is found in iodized salt, dairy products, seafood, and eggs. It plays a role in thyroid health and immune health, as well as fetal growth and brain development (1).
People who follow diets low in iodine-containing foods, such as vegan or vegetarian diets, could benefit from regular supplementation to reduce the risk of iodine deficiency.
Iodine is also an essential nutrient during pregnancy, when the RDA for iodine increases from 150 mcg per day to 220 mcg per day (1).
People who are pregnant or trying to become pregnant should consult a healthcare professional about taking a prenatal supplement that is appropriate for their needs.
Should I take iodine at night or in the morning?
There is no conclusive evidence for the best time of day to take an iodine supplement. However, several medications may have unwanted side effects if taken at the same time as iodine-containing supplements (1).
To avoid potential drug-nutrient interactions, it may be generally advised to take your iodine supplement at least 1 hour before or after taking any medications.
But the safest approach is to talk with a healthcare professional or registered dietitian to come up with a supplement regimen that’s best for you.
What is the most absorbable form of iodine?
A small study published in 2002 found that human participants absorbed 96.4% of potassium iodide (4).
More recently, a 2022 study evaluated the bioavailability of natural iodine from brown algae and found that up to 90% of iodine was absorbed in vivo (in a living organism) versus much lower absorption rates found in vitro (in a petri dish or test tube) (5).
What are the symptoms of low iodine?
Goiter is considered one of the earliest signs of low iodine, or iodine deficiency, and is often associated with hypothyroidism (1).
Goiter is characterized by noticeable swelling in the neck and may be accompanied by other symptoms, such as difficulty swallowing, a hoarse voice, or coughing.
Some of the more common signs of hypothyroidism are fatigue, weight gain, depression, a frequent cold feeling, and constipation.
Severely low iodine during pregnancy can result in fetal growth and development issues, miscarriage, or stillbirth (1).
Studies also suggest that people with chronically low iodine intake have a higher risk of thyroid cancer (1, 6).
The bottom line
Iodine is an essential mineral that supports the proper function of your thyroid gland.
Your thyroid gland plays a critical role in producing hormones that regulate growth and metabolism throughout your life.
If you suspect you have low iodine or may be at risk of developing iodine deficiency, consult a healthcare professional to determine whether an iodine supplement is right for you.
There are countless supplement options available. When choosing one that is best for you, be sure to consider the price, ingredient content, dosage, and overall quality before purchasing.