A complete safety, timing, and dosage guide for combining Vitamin K (K1, K2) with St. John's Wort — including how the two supplements interact, the best time of day to take each, and which populations should be careful.
Yes, you can safely take vitamin K (K1, K2) with St. John's Wort — no significant interaction has been reported.
Vitamin K (K1, K2) and St. John's Wort together are considered safe, with no significant interaction documented. Vitamin K supports blood clotting and bone health through its role as a cofactor for specific enzymes, while St. John's Wort affects mood through pathways in the brain. Because these two supplements do not meaningfully interfere with each other's absorption, metabolism, or activity, combining them is unlikely to cause problems for most people.
Vitamin K is a fat-soluble vitamin absorbed alongside dietary fats and packaged into chylomicrons for transport through the lymphatic system. St. John's Wort is widely known for inducing hepatic cytochrome P450 enzymes, particularly CYP3A4, which accelerates the breakdown of many medications and some supplements. However, vitamin K does not depend on cytochrome P450 metabolism for its physiological functions, so enzyme induction by St. John's Wort does not significantly lower vitamin K levels or alter its activity. While St. John's Wort can indirectly affect the anticoagulant warfarin by speeding its metabolism, this interaction involves the drug itself rather than vitamin K. Thus, there is no plausible biological mechanism for a meaningful interaction between vitamin K and St. John's Wort.
If you need both supplements, the simplest approach is to take vitamin K with a breakfast or dinner that contains healthy fat, and St. John's Wort 15–30 minutes before the same meal or on an empty stomach, depending on your tolerance. Since no interaction exists, there is no required spacing, but keeping them at separate times can help you build a steady daily habit. For best absorption, pair vitamin K with a source of fat and avoid taking St. John's Wort right before big meals if it bothers your stomach. If you miss a dose, take it as soon as you remember unless the next dose is within a few hours. Always use reputable brands and check with a pharmacist if you have any prescription medications, because St. John's Wort's enzyme-inducing effects can affect many drugs.
Vitamin K1 (phylloquinone) is plant-based and requires bile salts and dietary fat for optimal absorption, whereas vitamin K2 (menaquinone, especially MK-7) is more bioavailable with a longer half-life in circulation. St. John's Wort products are often standardized to hypericin or hyperforin, and hyperforin is the primary compound responsible for CYP enzyme induction. The neutral interaction applies to both vitamin K1 and vitamin K2, as neither relies on CYP3A4 for its function. Choosing a high-quality St. John's Wort extract with a known hyperforin content does not change the safety of this combination.
Yes, I can take vitamin K (K1, K2) and St. John's Wort at the same time safely. There is no known interaction between them, so I do not need to space out my doses. I might still take vitamin K with a fatty meal to help absorption.
Yes, it is safe to combine vitamin K with St. John's Wort every day. No evidence suggests that daily use together causes harm. However, I should keep my vitamin K intake consistent if I am taking any blood-thinning medication.
I don't need to wait at all between vitamin K and St. John's Wort, since they don't interact. If I take vitamin K with dinner and St. John's Wort in the morning, that's perfectly fine.
No, they do not compete for absorption. Vitamin K is absorbed along with dietary fats, while St. John's Wort compounds are absorbed independently through the intestine. I can take them together or separately without worrying about reduced absorption.
Most people can take them together safely, but I should avoid this combination if I am pregnant or breastfeeding unless my doctor approves. I also need extra caution if I take warfarin, antidepressants, birth control pills, or immunosuppressants, because St. John's Wort changes drug metabolism and can reduce effectiveness.
I should take vitamin K with a meal that contains fat to maximize absorption. St. John's Wort can be taken with or without food, though taking it at the same time each day is best. If St. John's Wort upsets my stomach, I can take it with a small snack.
Reviewed by Caroline M. on June 11, 2026 for accuracy against the sources listed above. This page is educational and is not a substitute for professional medical advice.
The matrix has 86 supplements and 7310 pairwise interactions. Click any cell to see the full breakdown.