What Is NAC Supplement?

Medically reviewed by Fallon Mumford, PharmD

NAC stands for N-acetylcysteine. It is the supplement form of cysteine, a non-essential amino acid that converts into the antioxidant glutathione in the liver. As an amino acid, cysteine also acts as a building block for proteins.

An inhaled, liquid form of NAC is a prescription drug approved by the U.S. Food and Drug Administration (FDA). Most commonly, NAC is used to treat acetaminophen (Tylenol) toxicity and certain respiratory conditions, including chronic obstructive pulmonary disease (COPD).

Since NAC is an FDA-approved drug, the use of NAC in dietary supplements is technically not permitted by the FDA. However, in August 2022 the FDA announced a consideration to change its stance on allowing consumer NAC supplements. The decision is still pending approval.

Dietary supplements are minimally regulated by the FDA and may or may not be suitable for you. The effects of supplements vary from person to person and depend on many variables, including type, dosage, frequency of use, and interactions with current medications. Please speak with your healthcare provider or pharmacist before starting any supplements.

Benefits of NAC

NAC appears to play a role in various facets of health, likely due to its function as an amino acid and as the precursor to a powerful antioxidant. Many benefits for the NAC supplement are still being researched.

May Help Treat Mental Health Disorders

NAC supplementation has been considered for the treatment of several psychiatric disorders. A research review examining this connection found a dose of 2000-2400 mg per day of NAC orally may be an effective adjunct treatment for schizophrenia and substance use disorders.

Researchers attribute this benefit to NAC’s anti-inflammatory and antioxidant effects that could improve brain health and modify neurological pathways.

May Reduce Irritability and Hyperactivity in People With Autism Spectrum Disorder

Some research has shown the benefits of NAC supplementation for people with autism spectrum disorder.

An analysis of research found 8-12 weeks of NAC supplementation resulted in less hyperactivity and irritability, and more social awareness in those with autism spectrum disorder (ASD).

Similarly, another analysis found taking antioxidants–including NAC–improved scores on the aberrant behavior checklist in those with ASD. This included reduced irritability and hyperactivity; however, the effect was small.

May Reduce Age-Related Health Conditions

NAC may help support healthy aging. Research found a combination of glycine and NAC supplementation improved some age-related health abnormalities in older adults. These included lowering measures of oxidative stress and systolic blood pressure and increasing gait speed and muscle strength.

How to Take NAC

NAC supplements can come in the form of a pill, powder, or effervescent tablets.

Some forms of NAC may have an unpleasant smell, similar to sulfur or rotten eggs. You may want to take the supplement alongside a flavored drink to mask the smell and taste.

Dosage

There is no current standard dose for NAC supplements. Since NAC supplements are not yet permitted by the FDA, it’s important to speak to your healthcare provider before taking NAC. They can recommend a safe dose for you, as well as how long you can safely take the supplement.

Is NAC Safe?

There have been no safety concerns reported on NAC supplement products.

However, there aren’t yet studies evaluating the safety of NAC among breastfeeding or pregnant individuals. Speak with a healthcare provider before taking NAC if you are pregnant or breastfeeding.

Potential Drug Interactions

NAC may interact with certain medications. You should not take NAC if you take anticoagulants, or blood thinners, as it may amplify the effect of these medications and the the effects of nitroglycerin.

NAC may also amplify the effect of anti-hypertensive medications, or drugs to lower blood pressure. When taken together, they can cause your blood pressure to drop too low.

For the same reasons, you should also avoid taking NAC supplements if you are taking other herbs or supplements that lower blood pressure or act as blood thinners. This might include L-arginine, niacin, stinging nettle, garlic, ginger, and gingko, among others.

What to Look For

The FDA is not able to regulate supplements for safety and effectiveness in the same way it regulates food and medications.

When buying a supplement, look for a product that has undergone third-party testing for purity and potency. Reputable third-party testers include U.S. Pharmacopeia, NSF International, and ConsumerLab.com.

When in doubt, you can always speak with a healthcare provider for product recommendations before starting a new supplement.

Can You Take Too Much NAC?

There is not an established maximum recommended dose for NAC supplementation, so it’s important to speak with a healthcare provider before taking NAC. Make sure to follow the dosage recommendation on the supplement label unless your healthcare provider recommends otherwise.

Side Effects of NAC

There are a few potential side effects of NAC oral supplements. These include:

• Nausea

• Vomiting

• Abdominal pain or discomfort

• Diarrhea

• Indigestion

A Quick Review

NAC is a derivative of the non-essential amino acid cysteine, which is a precursor to the antioxidant glutathione. A prescription drug form of NAC is FDA-approved, but the FDA does not yet permit the use of NAC in supplements. The FDA is currently in progress of updating their position on the topic.

NAC supplements have been studied for their use in treating psychiatric disorders, reducing hyperactivity and irritability in those with ASD, and improving age-related health abnormalities. Researchers attribute many of these potential benefits to NAC’s anti-inflammatory and antioxidant effects.

If you’re interested in taking NAC, speak with a trusted healthcare provider before adding this new supplement to your regimen.

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Read the original article on Health.