Can St. John’s wort products help?

Photo of a woman sitting near a tree (PantherMedia / Dmitrii Kiselev)

Some St. John’s wort products can relieve mild to moderate depression in the short term. They have not been proven to have the same effect in severe depression, though. Side effects are less common with St. John’s wort products than they are with some other antidepressants. But interactions with other drugs can occur.

Depression isn't the same as just feeling sad or down. Typical signs of depression include feeling very down for at least two weeks and a general lack of interest or motivation. People who are depressed usually sleep poorly, feel exhausted and have problems coping with everyday life. They lose their self-confidence, have a very negative self-image and often become withdrawn. They also have difficulty concentrating. Depression can be treated with psychological therapies and/or medication (antidepressants).

Treating depression with St. John's wort products

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

As with most herbal medicines (phytopharmaceuticals), many different St. John's wort products are available, with very different doses and ingredients. So there is no guarantee that the St. John's wort products you can buy will have the same effect as the extracts that have been tested in studies. A lot of products only have a very small dose of hypericum in them.

Following a change in German regulations on April 1, 2009, some St. John's wort products are now only available on prescription. This only affects those for moderate depression, though. The St. John's wort products that are used for different levels of depression, such as mild depression, are still available without a prescription.

Research on the effects of St. John's wort

A group of researchers from the Cochrane Collaboration looked for studies on St. John's wort products to find out whether they can relieve depression in adults, and how they compare to other medication for depression. The researchers included a total of 29 studies in their analysis, involving about 5,500 participants: 12 studies compared St. John's wort with a dummy drug (placebo), 11 studies compared it with other antidepressants, and 6 studies compared it with both a placebo and other antidepressants. The studies lasted between 4 and 12 weeks and tested very different St. John's wort products in various doses. Most of the participants in the studies had mild or moderate depression, and a few of the studies included people with severe depression. Around 7 out of 10 participants were women.

Results for participants with mild to moderate depression

The St. John's wort extracts used in the studies were found to relieve mild to moderate depression better than the placebo treatment. Studies that compared St. John's wort with other antidepressants showed a similar effect for both treatments. However, the studies did not include all commonly used antidepressants.

One serious problem with the studies is that the participants were only monitored for a few weeks. But depression often lasts longer or comes back after a while. So an important question for people with depression is whether St. John's wort helps in the longer term or can prevent further episodes of depression. The research that has been done so far can't answer these questions.

Also, the results of studies may not be true for every St. John's wort product because the many products you can buy have different doses and ingredients. In most of the studies, participants were given between 550 mg and 1,200 mg of St. John's wort per day. But the studies don't provide enough information to compare different extracts with each other or to find an optimal dose that is safe enough.

Results for participants with severe depression

The researchers found no evidence that St. John's wort helps to improve severe depression. Severe depression is a serious illness, and self-treatment with St. John's wort alone is unlikely to help.

Side effects and interactions with other medications

St. John's wort products can cause side effects such as nausea, minor skin irritations, sensitivity to light (photosensitivity) and headaches. Some people are allergic to the products themselves too. But St. John's wort is somewhat less likely to cause side effects than other antidepressants, such as SSRIs (selective serotonin reuptake inhibitors) or tricyclic antidepressants.

It may interact with other medications, though. In other words, taking St. John's wort at the same time as other medicines could increase or reduce the effect of the drugs. This particularly applies when taking St. John's wort at the same time as medication that slows down blood clotting (for example warfarin or "Marcumar"). It can weaken the effect of those drugs and increase the risk of blood clotting. St. John's wort also weakens the effect of drugs that influence the body's immune system (like cyclosporine, which suppresses the immune system). And there is some evidence that it can stop the contraceptive pill from working properly.

Because herbal medication such as St. John's wort can cause problems when taken in combination with other medications, it is important that anyone who is taking several medications is aware of the possible interactions. You should talk to your doctor before taking any medication, even if it is available over the counter.