N-acetyl Cysteine (nac) Interactions Overview

What's Going On With NAC Availability As A Supplement?

N-acetyl cysteine (NAC) was once available over-the-counter (OTC) as a dietary supplement, but it was later taken off the market after the FDA sent warning letters to companies selling NAC-containing supplements.

This caused some confusion about the legality of NAC as a supplement. The FDA does not allow NAC to be added to supplements because it was approved as a drug before it was marketed as a dietary supplement.

Recently, however, NAC has been reintroduced as an OTC supplement, but the FDA is still considering whether to allow its sale as a supplement. In August 2022, the FDA announced that it may permit the sale of NAC as a supplement in the future. In the meantime, the FDA will exercise discretion in enforcing rules for the sale and distribution of NAC supplements, as long as they comply with other laws.

What Is NAC Used For As A Dietary Supplement?

N-acetyl cysteine (NAC) is approved by the FDA for prescription use and is commonly used to treat acetaminophen (Tylenol) overdose, as well as various respiratory conditions (e.g. chronic bronchitis.

As an OTC dietary supplement, people use NAC for various reasons such as antioxidant support, liver support, and to promote the production of glutathione, a powerful antioxidant.

NAC is also often utilized as a performance enhancer, as it may reduce fatigue and improve exercise endurance. 

Other uses of NAC include:

• Improvement of cardiovascular health: Research shows that NAC may improve endothelial function, which is the ability of blood vessels to expand and contract as needed. This improvement in endothelial function may help to reduce the risk of heart disease.
• Anti-inflammatory Agent: NAC may help to reduce inflammation in the body, which is a key contributor to many cardiovascular diseases.
• Immunomodulatory Effects: NAC has been shown to have both anti-inflammatory and immune-boosting properties. NAC can help to regulate the production of cytokines, which are molecules that play a key role in the immune response.

Does NAC Have Drug Interactions?

N-acetyl cysteine (NAC) has the potential to interact with several types of drugs, leading to adverse effects.

Moderate interactions have been noted with activated charcoal, anticoagulant/antiplatelet drugs, antihypertensive drugs, and chloroquine.

Activated Charcoal

When taking N-acetyl cysteine with activated charcoal, there may be reduced effectiveness of the charcoal and reduced absorption of the N-acetyl cysteine.

Blood Thinning Drugs

N-acetyl cysteine may increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs. Research has shown that intravenous N-acetyl cysteine can decrease prothrombin time, prolong coagulation time, decrease platelet aggregation, and increase blood loss in surgical patients.

Antihypertensives

When taken with antihypertensive drugs, N-acetyl cysteine may increase the risk of hypotension. Animal research suggests that it can potentiate the hypotensive effects of some angiotensin-converting enzyme inhibitors (ACEIs), such as captopril and enalaprilat. Therefore, combining N-acetyl cysteine with other antihypertensive drugs may increase the risk of hypotension.

Chloroquine

There is a theoretical concern that N-acetyl cysteine may interfere with the antimalarial effects of chloroquine. Animal research suggests that N-acetyl cysteine may reduce the antimalarial effects of chloroquine by increasing cellular levels of glutathione. When taken with intravenous or transdermal nitroglycerin, N-acetyl cysteine can cause severe hypotension and intolerable headaches.

Drugs that interact with N-acetyl Cysteine (nac)