Osterly Market NAC 600 mg with Selenium

600 mg N-acetyl cysteine, with selenium. And a note the label does not carry.

N-acetyl cysteine at a stated dose, paired with selenium — plus the regulatory situation, which almost nobody selling NAC mentions.

What it's for

NAC is a form of the amino acid cysteine, and cysteine is the rate-limiting ingredient your body needs to build glutathione, its principal internal antioxidant. That is the whole reason people take it: swallowing glutathione itself works poorly, while NAC actually reaches the bloodstream and gets used. It has decades of medical history as a prescription mucolytic for thinning airway mucus, and it is the hospital antidote for paracetamol overdose — given intravenously, under supervision, at doses far beyond anything in this bottle. The selenium is here because it is a cofactor for the enzymes that recycle glutathione.

How to take it

• One capsule daily, with or without food
• NAC smells faintly of sulphur. That is normal and not a sign anything is wrong
• It has a mild blood-thinning effect. Mention it before surgery and if you take an anticoagulant
• If you or someone else has taken too much paracetamol, call emergency services. Do not try to treat an overdose with this. Hospital treatment is intravenous, dosed by weight and blood level, and it is time-critical
• Selenium accumulates. Check the panel against any multivitamin you already take — doubling up is easy and not harmless

On the label

• 600 mg N-acetyl L-cysteine per capsule
• Selenium included and stated
• 30 capsules or 120 capsules

What this is not

• Not an overdose treatment you administer yourself
• Not a hangover cure, whatever the internet says
• Not glutathione — it is the building block your body uses to make it

The straight answer

Worth knowing before you buy: the FDA's stated position is that NAC is excluded from the legal definition of a dietary supplement, because it was approved as a drug before it appeared in supplements. Since 2022 the agency has said it will exercise enforcement discretion, which is why it is still on shelves everywhere. Nothing about that makes it unsafe — but it is a genuinely unsettled category, and you should hear it from us rather than find out later.

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These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease. Talk to your doctor before starting any supplement, especially if you are pregnant, nursing, or taking prescription medication.