Short answer

We found no documented interaction between Milk thistle and NAC in the sources below. That isn't proof the combination is right for you: check each one's cautions, and ask your pharmacist if you take medication.

Milk thistle

What it is: A flowering plant whose extract, silymarin, is sold for liver health.

What the research says: There isn't enough good evidence to draw conclusions. Small studies suggest it may help blood sugar in type 2 diabetes; liver-disease trials have been conflicting.

Cautions

• Usually well tolerated; it can cause bloating, nausea or gas.
• It can trigger allergies in people allergic to ragweed, daisies or marigolds.
• Little is known about use in pregnancy or breastfeeding.

Medicines to check

• Talk to your clinician if you take any medicine

In Holitro: Milk Thistle (450 mg per capsule)

Source: NIH National Center for Complementary and Integrative Health: Milk Thistle: Usefulness and Safety (updated February 2025)

NAC (N-acetylcysteine)

What it is: An antioxidant that's both a hospital medicine (for acetaminophen overdose) and a supplement.

What the research says: As a medicine it treats acetaminophen poisoning. As a supplement, results for lung conditions and as an add-on for depression are mixed.

Cautions

• It can cause stomach upset, nausea, diarrhea, tiredness or rash; less often low blood pressure or headache.

Medicines to check

• Nitroglycerin: don't combine (severe headaches, lower blood pressure)
• Antidepressants: animal studies suggest NAC may strengthen their effect
• Cancer treatment: check with your care team

In Holitro: NAC (600 mg per capsule)

Source: Memorial Sloan Kettering Cancer Center, About Herbs: N-Acetylcysteine (updated October 2022)

Check with your doctor or pharmacist, especially if you take medication.

Check your stack — free

Educational information only, not medical advice. This reflects general ingredient overlap, not a personalized safety review. Always check with your doctor or pharmacist before combining supplements, especially if you take medication, are pregnant or nursing, or manage a health condition. These statements have not been evaluated by the FDA.