St John's Wort
Browse St John's wort capsules, tablets, tinctures and dried herb. We explain how extracts are standardised to hypericin, how the forms differ, and which medicines and situations call for extra care before you start.Read more →
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Hypericum perforatum: extracts, hypericin and how the forms differ
St John's wort is the dried flowering top of Hypericum perforatum, a yellow-flowered plant that grows across Europe and one of the best known entries in our herbs and plants range. Growers harvest the aerial parts: the flowering tops, leaves and upper stems. Those parts are dried, then either milled for tea and tinctures or extracted with alcohol or water to make a concentrated powder.
Hypericin and hyperforin decide what is on the label
Two plant compounds shape how a product is described. Hypericin is the marker used to standardise extracts. Most capsules and tablets state 0.3% hypericin, so each batch delivers the same measured amount. Hyperforin is the compound linked to interactions with medicines. The European Medicines Agency uses a daily hyperforin intake below 1 mg as the point at which the standard interaction warnings may be left off a herbal product. That is why low-hyperforin extracts exist alongside whole-herb preparations.
You will also see an extraction ratio, written as 4:1 or 6:1. It tells you how much dried herb went into the extract. This is why one capsule with a few hundred milligrams of dry extract can list an equivalent of well over a gram of herb. Comparing two products on the milligram number alone is misleading. Compare the standardised hypericin per serving instead.
The forms we carry and what separates them
- Capsules and tablets: standardised dry extract, a fixed dose per serving, easiest to keep consistent.
- Tinctures: alcohol-based drops, flexible dosing, faster to adjust, as with other herbal drops such as rhodiola preparations.
- Dried herb: loose flowering tops for tea, the traditional preparation, with the least predictable strength.
- Infused oil: the red oil made by steeping flowers in vegetable oil, for use on the skin, not for swallowing.
How we choose the St John's wort in this collection
Three things decide whether a product joins the range: the preparation, the standardisation and the dose per serving. We prefer extracts that print their hypericin content and their extraction ratio, because those two numbers are what let you compare one bottle with another. We also stock plain dried herb and tinctures for people who prefer them, and we say plainly which is which. We buy straight from the brands, so stock is authentic, and every product passes our compliance team before it goes live. Want the detail? Read how we select brands and products.
Who it suits and when to be careful
This collection is for adults who want a clearly labelled herbal preparation and are willing to take it as a daily routine rather than now and then. Sticking to one product keeps your dose the same, which is the main reason people get confused when they switch brands. Be honest with yourself about timing too: herbal extracts are used over weeks, not days.
Some situations call for a conversation with your GP or pharmacist first. St John's wort affects the liver enzymes CYP3A4, CYP2C9 and CYP2C19 and the transporter P-glycoprotein, which is how it changes the way many prescription medicines are broken down. It can also make skin more sensitive to sunlight and UV lamps. It is not for use during pregnancy or breastfeeding, and not for children. Shoppers weighing up their options often look at ashwagandha capsules in the same visit.
Frequently asked questions
St John's wort is a herb, Hypericum perforatum, with small yellow flowers and leaves that show translucent dots when you hold them to the light. Those dots are oil glands. The parts used are the aerial parts: flowering tops, leaves and upper stems, harvested and dried. From there they are sold as loose herb, as an alcohol tincture, or as a concentrated dry extract in capsules and tablets.
It depends on how precise you want your dose to be and how you like taking things. Standardised capsules and tablets give the most consistent amount per serving. Tinctures let you adjust in drops. Dried herb is the traditional tea preparation and varies most from batch to batch. Infused oil is a skin product only.
| Form | Dose consistency | Suits |
|---|---|---|
| Capsules | High | Daily routine |
| Tablets | High | One-a-day users |
| Tincture | Medium | Flexible dosing |
| Dried herb | Low | Tea drinkers |
| Infused oil | Not oral | Skin use |
Hypericin is the marker compound used to standardise St John's wort extracts. A label reading 0.3% hypericin means the maker measures each batch and adjusts it so the same proportion is present every time. Without standardisation, plant material varies with harvest, weather and origin. It is the most useful number for comparing two products, more useful than the headline milligram figure on the front of the pack.
Because some labels state the dry extract and others state the herb equivalent. An extraction ratio such as 6:1 means six parts dried herb were concentrated into one part extract. So a capsule holding a few hundred milligrams of extract can honestly list an equivalent of one to two grams of herb. Neither number is wrong. To compare fairly, look at the extract weight and the standardised hypericin per serving.
Follow the dose printed on the pack you bought, since strengths differ widely between products. Many capsules and tablets are taken with food, either once a day or spread across the day. Taking it with a meal is the usual advice for anyone who finds herbal extracts sit heavily. Keep to one product rather than switching, so your daily amount stays the same, and take it at roughly the same time each day.
Quite a few, which is why this deserves a proper answer. St John's wort induces the liver enzymes CYP3A4, CYP2C9 and CYP2C19 and the transporter P-glycoprotein. That can lower the blood levels of medicines such as hormonal contraceptives, warfarin, ciclosporin, antiretrovirals and some cancer medicines, making them less effective. It should also not be combined with antidepressants. If you take any prescription medicine, speak to your GP or pharmacist before you start.
It can. Skin reactions after exposure to sunlight or UV lamps are a known possibility with St John's wort preparations, and they are more likely at higher intakes. The practical advice is straightforward: avoid sunbeds and strong midday sun while you are taking it, and cover up or use sunscreen on bright days. If a rash or unusual redness appears, stop taking it and speak to a pharmacist.
No to the first two. St John's wort is not recommended during pregnancy or breastfeeding, and it is not intended for children or teenagers. Before planned surgery, tell your doctor you take it and follow their instruction on stopping, because it can affect how anaesthetic and other medicines are processed. Anyone with an existing health condition should check first. For a gentler herbal routine in the evening, some people look at valerian root supplements instead.
Hyperforin is the constituent most associated with medicine interactions. The European Medicines Agency treats a daily hyperforin intake below 1 mg as the threshold below which the usual interaction warnings may be omitted from a herbal product. Extracts can be produced to keep hyperforin low, while whole dried herb and tea contain whatever the plant delivered. If a product does not state its hyperforin content, assume it is not a low-hyperforin preparation.
