N-Acetylcysteine & the Eye

N-acetylcysteine, also known as NAC, is an amino acid that may help prevent recurring bronchitis and cancer, as well as help treat conditions such as pulmonary diseases and cirrhosis. In addition to these possible benefits, N-acetylcysteine may also provide some help with eye conditions. If you think NAC may help you, talk with your doctor and she will help you evaluate any potential associated risks to determine the most appropriate treatment for your eyes and general health.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.


Blepharitis is an eye condition that results in eyelid inflammation, redness and eye irritation. In your eyelids you have oil glands, called meibomian glands, and blepharitis often occurs when these glands fail to function properly. You may have flaking in your eyelashes, much like dandruff, and these flakes can make their way to the surface of your eye and result in irritation. Once you have blepharitis, the condition does not typically resolve completely, and you may find that you have recurrent episodes. N-acetylcysteine may help improve the function of the meibomian glands, reports the Bastyr Center for Natural Health. This could help reduce the occurrence of blepharitis and associated symptoms.

Dry Eye

The surface of your eye requires a tear film that helps protect and nourish the surrounding tissues. If you do not have enough tears, you may experience dry eye, a condition that causes stinging, itching and redness. You may also have times when your vision suddenly blurs, but, in most cases, blinking for a few seconds will restore vision. Artificial tears may offer momentary relief from these symptoms. As of 2011, the Medical University of Vienna researchers are preparing to study the effects of eye drops containing N-acetylcysteine in relation to dry eye symptoms 2.

Side Effects

Side effects of N-acetylcysteine supplements may include gastric upset, such as nausea, vomiting and diarrhea. You may also experience tiredness, headaches, low blood pressure and skin rash. In some cases, N-acetylcysteine may also cause irritation to your conjunctiva, the thin tissue that covers the white of your eye and the underside of your eyelids.


You should not use supplements containing N-acetylcysteine without first consulting your doctor. Despite the potential benefits for some eye conditions, this supplement may not offer the best methods of treatment or protection for your eyes, and your doctor can help you determine appropriate alternatives.