NAC (N-Acetyl Cysteine) Explained: What the "N-Acetyl" Means

By the Zespo team · Updated 26 October 2026

NAC stands for N-acetyl cysteine (also written N-acetyl-L-cysteine). It is the amino acid cysteine with an acetyl group attached to its nitrogen atom, which is what the "N-acetyl" in the name refers to.

What is cysteine?

Cysteine is a sulphur-containing amino acid. The body can make it, and it is also found in protein foods such as eggs, curd, paneer, legumes, oats, onions and garlic. Its sulphur is part of the reason eggs and onions have their distinctive smell.

On the label

NAC is a white powder with a slight sulphur smell, usually supplied in capsules and listed in milligrams per serving, commonly 600 mg.

Speak to a doctor before use if you take regular medication, are pregnant or nursing.

What to check before you buy

• The amount of each ingredient per serving, not just per capsule
• How many capsules make one serving and how many servings are in the pack
• Whether any ingredient sits inside an undisclosed "proprietary blend"
• An FSSAI licence number and the veg/non-veg mark on the pack

Label facts: Zespo NAC (N-Acetyl Cysteine) 600 mg - 90 Veg Capsules

• 600 mg per single-capsule serving - the standard studied strength
• Single ingredient, no blend, 90 servings per bottle
• Made in India in a GMP-certified facility, FSSAI-licensed

See Zespo NAC (N-Acetyl Cysteine) 600 mg - 90 Veg Capsules on zespo.in · Also on Amazon.in (search "Zespo").

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Zespo products are food supplements, not medicines. This article is for general information and is not medical advice. Take supplements as directed on the label and speak to a qualified healthcare professional if you are pregnant, nursing, taking medication or have a medical condition.