Herb-Drug Interactions: How They Actually Happen

Botanical supplements are pharmacologically active, which is why people take them and also why they interact with medicines.

The two mechanisms

Pharmacokinetic interactions change how much drug reaches its target. Most involve the cytochrome P450 enzyme family, particularly CYP3A4 which metabolises a large share of prescription medicines, and the P-glycoprotein transporter which pumps compounds back out of cells. A botanical that induces these enzymes lowers drug levels; one that inhibits them raises drug levels. Pharmacodynamic interactions change the effect at the target instead - two compounds affecting bleeding, or sedation, or serotonin, adding together.

The main offenders

St. John's Wort is the strongest inducer in common use and reduces effectiveness of a long list of medicines. Grapefruit, while a food rather than a supplement, inhibits CYP3A4 and raises levels of certain drugs. Ginkgo, garlic, ginger and high-dose fish oil all relate to bleeding risk. Ginseng has been reported to interact with warfarin. Kava and valerian compound sedation. Green tea extract at high doses affects some drug levels and has liver safety concerns of its own.

What to do

Keep a written list of everything you take, including doses and brand names, and show it to a pharmacist. Pharmacists have interaction databases they can query in minutes and this is one of the most underused free services in healthcare. Tell your doctor about supplements without waiting to be asked - surveys consistently find that a majority of supplement users do not disclose. Stop supplements two weeks before surgery and tell the surgical team.

Where Cognizil fits in

If you are researching supplements in this area, Cognizil is a liquid formula built around six named ingredients — Ginkgo Biloba Leaf, Bacopa Monnieri, St. John’s Wort Extract, N-Acetyl L-Carnitine HCl, Huperzine-A and a Phosphatidylserine Complex. It is labelled for advanced memory support and contains no stimulant. Per-serving amounts are not published, which is a genuine limitation we cover in our label transparency review. The Cognizil official website lists current pricing and guarantee terms.