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Overview: Humic acid is a natural substance that forms when plant and animal matter breaks down. It is sold as an over-the-counter dietary supplement and is sometimes combined with a related substance called fulvic acid. People often take humic acid for digestive and gut health, immune support, and antioxidant or anti-inflammatory support, but these benefits are not well defined. Because humic acid is poorly studied in humans, its common side effects are not well known. Before taking humic acid, tell your health care provider about any health conditions you have and about any medicines you are taking.

Uses

What is humic acid used for?

Humic acid supplements, sometimes combined with a related substance called fulvic acid, are commonly used for the following reasons, but their benefits for any use are not well defined.

  • Digestion and gut health
  • Antioxidant and anti-inflammatory support
  • Immune system support 
  • General wellness 
  • To help the body remove certain metals and toxins

Note: The FDA has not reviewed humic acid for safety and effectiveness. Learn more about dietary supplements here.

How does humic acid work (mechanism of action)?

Humic acid is not a single chemical. It is a mix of many natural substances that form when plant and animal matter breaks down over a long time. Humic acid is found in soil, peat, water, and coal-like deposits (such as leonardite). It is one of the main parts of a larger group called humic substances, which also includes fulvic acid and humin.

Humic acid is a mixture of large, complex molecules that carry many reactive chemical parts called functional groups. These functional groups are thought to be the main reason humic acid may act as an antioxidant and may bind to metals and other substances.

In laboratory and animal research, humic acid has had mixed effects. In some studies, it soaked up unstable molecules called free radicals and lowered inflammation signals called cytokines. In other studies, it did the opposite and damaged certain cells. In laboratory, animal, and limited human studies, humic acid has been linked to changes in gut bacteria and less inflammation in the bowel.

In laboratory tests, humic acid can also bind to metals and other molecules. Humic acid products are sometimes sold as a “detox,” but there is no proof that humic acid removes harmful metals from the human body. Plus, this same binding may affect minerals your body needs, such as iron, calcium, and zinc.

The benefits of humic acid are not well defined. Most of what is known comes from laboratory and animal research. Evidence in humans is limited, so it is not clear how well humic acid works for any specific health purpose in people.

Humic acid supplements are natural products. The way humic acid is made, and its exact makeup, can change depending on the source material it comes from. Because of this, the amount and type of active substances in a specific humic acid product may vary. These differences may change the effects or side effects of one product compared to another.

How should I store humic acid?

You should store humic acid according to the product label. Most dietary supplements should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.

Side Effects

What are the most common side effects of humic acid?

There is not enough research to know what the common side effects of humic acid may be. Tell your health care provider if you have any side effects that bother you.

There may be side effects of humic acid that are not listed here. Contact your health care provider if you think you are having a side effect of a supplement. In the U.S., you can report side effects to the FDA at www.safetyreporting.hhs.gov or by calling 888-SAFEFOOD (888-723-3366). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of humic acid?

While less common, the most serious side effects of humic acid are described below, along with what to do if they happen.

Severe Allergic Reactions. Humic acid may cause allergic reactions. Stop taking humic acid and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Thyroid Problems. Humic acid may act on the thyroid gland. It can bind iodine, which the thyroid needs to work, and it may lower the amount of thyroid hormone in the body. Over time, this could lower thyroid activity, which is called hypothyroidism. People who already have thyroid problems or low iodine levels may be at a higher risk. Talk to your health care provider before using humic acid, and tell them right away if you have any of the following.

  • Unusual tiredness or weakness
  • Weight gain you cannot explain
  • Feeling cold when others do not
  • Dry skin, constipation, or a slow heartbeat

Warnings & Precautions

Who should not use humic acid?

Allergies to Ingredients. People who are allergic to any of the following should not take humic acid.

  • Humate
  • Humic acid
  • Humic substances
  • Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific humic acid products they stock.

What should I know about humic acid before using it?

Humic acid is a dietary supplement. It cannot be marketed to treat or cure a disease.

Humic acid is available in several forms. Common forms include liquid drops, powders, and capsules, and it is sometimes combined with fulvic acid. It is also sold in some products that are applied to the skin. Read and follow the directions on the specific product you are taking, or take it as recommended by your health care provider.

If you use a liquid humic acid product, follow the label for how to measure a dose, usually with the dropper provided. If you use a powder, follow the label for how to measure a dose, usually by a scoop or by weight in grams.

Because humic acid comes from soil, peat, and coal-like deposits, the makeup of products can vary. Products may also contain trace metals, such as lead, arsenic, or mercury. Amounts may vary greatly between products. Choose products tested by an independent third-party organization and from a maker you trust. Ask your health care provider before use if you have questions about a specific product.

Keep humic acid out of the reach of children.

The FDA has not tested humic acid products to confirm that they contain the ingredients stated on their labels. Some dietary supplements have been tested by third-party organizations to confirm that they contain the ingredients listed on their labels and do not contain any harmful chemicals. Learn more about how to choose a safe dietary supplement product here.

What should I tell my health care provider before using humic acid?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if humic acid is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • Thyroid problems, such as an underactive thyroid (hypothyroidism) or a goiter
  • An autoimmune condition 
  • Digestive problems 
  • Kidney problems
  • Liver problems

Other Medicines and Supplements. Before taking humic acid, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how humic acid could affect pregnancy or harm a fetus. Tell your health care provider if you are pregnant or plan to become pregnant.

Breastfeeding. It is not known if humic acid passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.

Interactions

Does humic acid interact with foods or drinks?

There are no known interactions between humic acid and foods or drinks, but this has not been well studied.

It is unknown if drinking alcohol will affect humic acid.

Does humic acid interact with medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using so they can watch for any potential interactions.

In particular, make sure that you discuss if you are using any of the following before taking humic acid.

  • A thyroid medicine, such as levothyroxine, which is used to raise thyroid hormone levels
  • A medicine that suppresses your immune system, such as azathioprine (Imuran), cyclosporine (Neoral, Sandimmune), mycophenolate (CellCept), sirolimus (Rapamune), or tacrolimus (Prograf)

Humic acid might affect the absorption of some medicines or supplements, though this has not been confirmed in people. Tell your health care provider about all medicines that you take or have recently taken.

The interactions between humic acid and medicines are not fully understood. As with most dietary supplements, the research on drug interactions with humic acid is incomplete. Always check with your health care provider before taking humic acid with any medicines.

Overdose/Missed Dose

What should I do if I accidentally use too much humic acid?

If you or someone else has used too much humic acid, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

Humic acid supplements are available in several forms, including liquid drops, powders, and capsules. These products are sometimes combined with fulvic acid. Read the product label closely and speak to a health care provider about how to use humic acid safely. Do not take double or extra doses, even if you miss a dose.