Can St. John’s wort products help relieve depression?

People with milder cases of depression often use herbal remedies with St. John's wort extracts in them. Some of these products use the Latin name for St. John's wort: Hypericum perforatum, or simply hypericum.

As with most herbal medicines (phytopharmaceuticals), The strength of the commercially available St. John's wort products and other ingredients they contain vary greatly. Many over-the-counter products only have a very small dose of hypericum in them, for instance. This means that different products may have different effects, and won't necessarily work like the products tested in the studies did.

St. John’s wort products for moderate depression have to be prescribed by a doctor. They have specified doses. But no prescription is needed for products to treat mild depressive mood disorder. Those contain very different doses and ingredients.

A group of researchers analyzed a total of 35 studies involving nearly 7,000 participants. They wanted to find out whether St. John's wort products can relieve the symptoms of depression in adults, and how they compare to other medications. The studies lasted at least four weeks and tested a wide range of St. John's wort products. In most of these studies the participants used St. John's wort at doses of between 500 and 1,200 mg per day. The study participants had mild to moderate depression. The majority of them were women.

The St. John's wort products used in the studies were found to relieve mild to moderate depression better than the placebo treatment did. Studies that compared St. John's wort with other antidepressants showed that the treatments were similarly effective.

Only few of the studies lasted more than eight weeks. But depression often lasts longer than that or comes back after a while. There isn't enough research on whether St. John's wort products are effective over the long term or can prevent further episodes of depression.

The researchers found no evidence that St. John's wort helps in severe depression. Severe depression is a very serious disease and should not be treated with St. John's wort alone.

St. John's wort products can cause side effects such as nausea, minor skin irritations, sensitivity to light (photosensitivity) and headaches. They may trigger allergic reactions too. But the side effects are somewhat less common than those of other antidepressants.

Interactions with medications may occur when St. John's wort products are used – that means that they could increase or decrease the effect of other medications taken at the same time. For instance, St. John's wort reduces the effect of medicines that slow down blood clotting or suppress the body's immune system. And there's some evidence that it can make birth control pills less reliable.

Like conventional medicines, plant-based medicines such as St. John's wort may cause problems when used together with other medications. So it's important to be aware of possible interactions when taking more than one medication – and to not take over-the-counter medicine without consulting your doctor.