N-acetylcysteine (NAC)

General Information:

N-acetylcysteine (NAC), the active ingredient in Cysteplus, is a sulfur-containing amino acid. It is the precursor of the amino acids L-cysteine and glutathione. Glutathione is the primary antioxidant in the body. Because of this, NAC is a very powerful antioxidant itself.

Most NAC supplements have a strong sulphur smell and taste, making them hard to give to dogs and cats. Cysteplus is so highly refined, it has far less sulphur taste, making it much easier to give to dogs and cats.

NAC is an essential amino acid, meaning we need to supply it in the diet since it is not made within the body. Supplementation provides a number of beneficial effects.

It is a mucolytic agent: it clears mucus and phlegm from the respiratory system.

Animal and human studies of NAC proven this antioxidant activity.

In addition to antioxidant activity, NAC is effective in promoting normal liver detoxification.

N-Acetyl Cysteine (NAC) is cysteine and a sulfhydryl group, enabling it to interact with disulfide bonds.

The mucoprotein disulfide bonds are strengthened by NAC, making for a better mucus layer in the pulmonary system and intestinal tract.

Some uses for NAC include:

  • Liver Disease - protects against liver toxins
  • Pulmonary diseases and chronic bronchitis - cleans harmful debris out of the lungs
  • Detoxification - enhances several areas of the body's detoxification system
  • Enhanced glutathione levels - glutathione is the body's number one antioxidant
  • Antioxidant support, glutathione support

How NAC might work:

Cysteine is an amino acid that is closely related to cystine. (Cystine is two cysteine molecules combined together.) Cysteine is a sulfur-containing amino acid. It is important in helping with the formation of keratin and in enhancing keratin's strength. (Keratin strengthens beaks, nails, feathers, hair, and skin.) It is a vital component of the detoxification pathways of the liver and intestines. It is also a free-radical scavenger and antioxidant. The antioxidant properties are largely due to its ability to bind with an acetyl group, becoming N-acetyl-D-cysteine (NAC). NAC seems to function by increasing the available levels of reduced glutathione3. Glutathione is the body's most important antioxidant.

A lot of interest has been generated in this fact. It is well understood that optimal levels of antioxidants will prevent aging, cancer, degenerative disease, and organ damage. Because of this, nutritional medicine has long sought ways to increase reduced glutathione levels. Glutathione is available as a supplement, but it is expensive and may not be absorbed intact through the intestines when taken orally. All antioxidants, including the inexpensive ascorbic acid, will increase levels of reduced glutathione. The question becomes, which product is the most cost-effective? The only answer that seems clear is that supplementation with reduced glutathione is not the most cost-effective method.

Western medicine has been using NAC as an agent to enhance and moisten the mucus layer in the respiratory system. A fluid mucus layer literally sweeps out debris from the lungs. One product used in medicine is called Mucomyst, which is pure NAC administered by the use of a nebulizer. NAC seems to be just as effective at breaking down mucus when given orally, and the cost becomes less than the use of a product like Mucomyst.

NAC is extremely safe, only extremely high levels have ever shown any toxicity.


Acetylcysteine is a derivative of cysteine; an acetyl group is attached to the nitrogen atom. It is used as a cough medicine because it breaks disulfide bonds in mucus and liquefies it, making it easier to cough up. Its ability to break disulfice bonds makes it useful in thinning the abnormally thick mucus in collapsing trachea dogs and laryngeal paralysis dogs.

Because of its ability to enhance the production of Glutathione (the body's most important antioxidant), it is helpful in many degenerative diseases or chronic diseases.

Research suggests NAC is capable of enhancing immunity. In a double-blind, placebo-controlled trial, NAC was shown to positively impact lymphocyte cell numbers, the body's cells that produce antibodies.

NAC helps maintain good pulmonary health due to its mucolytic activity. NAC's sulfur cleaves bonds in mucoproteins, causing mucus to be subsequently broken into smaller, less viscous pieces. NAC has been noted to decrease the viscoelasticity of nasal mucus and increase the clearance of mucus by the cilia by thinning of secretions, thus helping maintain good pulmonary health.

As a sulfur source, NAC stimulates glutathione (an important antioxidant produced in the body) synthesis and activity, promotes liver detoxification, and is a powerful molecule capable of scavenging free radicals.

NAC has been shown to be effective in countering a number of liver toxins, including acetaminophen (Tylenol), poisonous mushrooms, and fungal toxins in food (mycotoxins).

Indications for Use:

  • Animals that live in homes with smokers
  • Asthmatic cats
  • Animals with chronic coughs
  • Animals that have been diagnosed with respiratory disease
  • As a part of a detoxification program
  • Liver disease; for liver disease, also see: Hepagen-C or Hepagen-Fc
  • Tylenol or acetaminophen toxicity
  • Other liver toxins, including aflatoxin poisoning (for information on aflatoxin poisoning click here)
  • Inflammatory conditions, including arthritis, degenerative joint disease, Inflammatory Bowel Disease, and Colitis.
  • Collapsing trachea
  • Laryngeal paralysis
  • Antioxidant support in chronic disease



  • 1-25 lbs=1/2 capsule twice daily
  • 25-50 lbs=1 capsule twice daily
  • 50-100 lbs= 2 capsules twice daily
  • This product has an objectionable taste when opened and placed on food. Start with a small amount to improve taste acceptance and then work up to full dose.


  • 1/2 capsule daily
  • This product has an objectionable taste when opened and placed on food. Start with a small amount to improve taste acceptance and then work up to full dose


  • All birds can receive approximately 1/32 capsule mixed into food daily
  • "Salt" food lightly with this product twice daily


  • Ferrets can have 1/- to 1/2 capsule daily in divided doses
  • This product has an objectionable taste when opened and placed on food. Start with a small amount to improve taste acceptance and then work up to full dose
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