Most trials gave 900 mg a day of a standardised extract, split into 3 doses of 300 mg. A capsule of whole herb is a different thing.
Our label says 1000 mg, and this page explains why that is not a bigger dose.
Quick Answer: How Much St. John's Wort Should You Take?
Most depression trials used 900 mg a day of a standardised extract, taken as 300 mg 3 times daily, and some specified 0.3% hypericin. An extract is concentrated from more herb, so 1000 mg of whole herb is not a larger dose. Interaction risk tracks hyperforin, which a herb capsule does not state, so check your medicines first.
Key Takeaways
- Trials typically used 900 mg a day of extract, as 3 doses.
- 8 trials in 1 review used 0.3% hypericin with 1 to 4% hyperforin.
- Our capsule holds 1000 mg of whole herb, not concentrated extract.
- Powdered herb at 2.7 g daily still cut midazolam exposure by 48%.
- Hyperforin under 1 mg a day was linked to fewer interactions.
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The Trial Dose
Almost every positive depression trial used an extract rather than powdered herb, and the doses cluster tightly.
| Trial | Daily dose | Form |
|---|---|---|
| US trial, 2001 | 900 mg, raised to 1200 mg | Standardised extract |
| US trial, 2002 | 900 to 1500 mg | Named extract, LI-160 |
| German trial, 2005 | 900 mg, up to 1800 mg | Named extract, WS 5570 |
| Contraceptive trial, 2003 | 600 or 900 mg | Extract, 300 mg per dose |
Why people take it at all is covered in the full picture of this herb.
Hypericin and Hyperforin
Labels and reviews name 2 marker compounds, and they do different jobs.
- Hypericin: A red pigment and the usual standardisation marker.
- Typical figure: 0.3% hypericin in many trial extracts.
- Hyperforin: The constituent that switches on the drug-clearing enzyme.
- Typical figure: 1 to 4% hyperforin in some trial extracts.
Of 35 studies in a 2016 review, 8 used an extract combining 0.3% hypericin and 1 to 4% hyperforin.[1]A systematic review of St. John's wort for major depressive disorder — Systematic Reviews (2016) View source
Hypericin is the figure most labels print, but hyperforin is the potent activator of the receptor that switches on CYP3A4, and it decides how strongly the herb interacts.[2]St. John's wort induces hepatic drug metabolism through activation of the pregnane X receptor — PNAS (2000) View source
What a 1000 mg Herb Capsule Is
Our label says 1000 mg, which sounds like more than 900 mg. It is not a like-for-like number.
- An extract: Concentrated from a larger weight of herb.
- A herb capsule: Dried flowers and leaves, nothing concentrated.
- Standardisation: An extract states its hypericin, sometimes hyperforin.
- Ours: Sold as whole herb, with no hypericin or hyperforin figure.
- The result: No fixed conversion to the trial doses.
We do not claim our 1000 mg herb capsule matches the trial extracts, and we would rather say so here than let 2 similar numbers imply it.
Why Whole Herb Still Interacts
A fair guess is that an unconcentrated herb must be gentler on your other medicines. The measurements say otherwise.
| Daily product | Hyperforin | Cut in midazolam exposure |
|---|---|---|
| Whole-herb powder tablets, 2.7 g | 12 mg | 47.9% |
| Powder almost free of hyperforin | 0.13 mg | 21.1% |
| Threshold in a 2019 review | Under 1 mg | Fewer major interactions |
In a 2006 trial of 42 men, 2.7 g a day of powdered herb still cut exposure to the marker drug midazolam by 47.9%.[3]The extent of induction of CYP3A by St. John's wort varies among products and is linked to hyperforin dose — European Journal of Clinical Pharmacology (2006) View source
A 2019 review suggested staying at or below 1 mg of hyperforin a day to minimise risk.[4]Understanding drug interactions with St John's wort (Hypericum perforatum L.): impact of hyperforin content — Journal of Pharmacy and Pharmacology (2019) View source A herb capsule gives no such figure, so treat it as interacting with the medicines hyperforin interferes with.
Timing, Duration and Stopping
None of these was tested head to head, so they are stated as practice rather than proof.
- Timing: Trials split doses 3 times a day; 1 daily capsule is a convention.
- Time of day: Morning, if sleep is affected.
- Duration: Mostly studied for 4 to 12 weeks.
- Stopping: The enzyme effect fades over about 7 days.
After 14 days on the herb, CYP3A activity returned to its starting level about 7 days after the last dose.[5]The recovery time-course of CYP3A after induction by St John's wort administration — British Journal of Clinical Pharmacology (2008) View source
Any dose also carries the side effects to watch for, and higher doses raise light sensitivity a little.
Counting Every Source
The dose that matters is the total from every product, not the number on 1 label.
- Blends: Some mood formulas contain it, including our Depression Tamer.
- Teas and tinctures: Unmeasured strength, the same interactions.
- 2 products at once: Never take 2 that both contain the herb.
- The pharmacist: Show them everything, including supplements.
Kept as your only source, a single capsule is 1 measured amount of 1 herb, described for what it is.
Speak to a Clinician Before Taking St. John's Wort If
- You take any prescription medicine, because this herb speeds up how the body clears many of them
- You take an antidepressant or any other medicine that acts on serotonin
- You rely on the pill or another hormonal method to prevent pregnancy
- You take warfarin, digoxin, cyclosporine, tacrolimus or any HIV medicine
- You are pregnant or breastfeeding, or have ever had a manic episode
- You have any thought of self-harm, which needs same-day help: call or text 988 in the US
Frequently Asked Questions
What's the best time of day to take St. John's Wort? +
No trial compared timings. Trials split the dose 3 times a day, and if sleep suffers, a morning dose is the sensible 1 change.
Can St. John's Wort be stopped abruptly? +
The reviews we used do not describe a withdrawal syndrome. The enzyme effect persists for about 7 days, which matters for your other medicines.
How do you feel after taking St. John's Wort? +
Mood effects were measured after 4 to 12 weeks, not hours. Early effects are more often side effects, such as stomach upset or restlessness.
What does St. John's Wort do to your brain? +
Its antidepressant mechanism is not settled, and hyperforin is 1 constituent with described activity. It adds to serotonin effects, which is why SSRIs are off limits.
How much St. John's Wort should I take? +
Trials used 900 mg a day of standardised extract as 3 doses of 300 mg. A whole-herb capsule has no direct conversion to that figure.
What is hypericin? +
A red pigment in the plant and the usual standardisation marker, often 0.3% of an extract. It is not what drives the drug interactions.
What is hyperforin? +
The constituent that switches on CYP3A4. In a 42-person trial, interaction size tracked hyperforin dose.
Is 1000 mg of herb the same as 900 mg of extract? +
No. An extract is concentrated from more herb, so the 2 numbers measure different things.
Does a tea or tincture interact less? +
Not reliably. Their hyperforin content is unknown, so treat them as fully interacting; 1 product can be enough to lower drug levels.
How long can you take St. John's Wort? +
NCCIH says it appears safe for up to 12 weeks in adults on no other medicine, and some studies suggest a year or more.
Related Reading
- Mild, Moderate and Major Depression Compared
- St. John's Wort and Hormonal Contraception
- Combining It With an Antidepressant
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