St. John's wort (Hypericum perforatum) has a history of medicinal use dating back to ancient Greece, where it was used to treat a range of illnesses, including various "nervous disorders." St. John's wort also has antibacterial and antiviral properties and, because of its anti-inflammatory properties, has been used topically to help heal wounds and burns. St. John's wort is one of the most commonly purchased herbal products in the United States.

In recent years, there has been renewed interest in St. John's wort as a treatment for depression and there has been a great deal of scientific research on this topic. In general, most studies have shown that St. John's wort may be an effective treatment for mild-to-moderate depression, and has fewer side effects than most other prescription antidepressants. But the herb interacts with a wide variety of medications, so it is important to take it only under the guidance of a health care provider.

It is also important to note that severe depression (characterized by an inability to function with daily activities, thoughts of suicide or of harming yourself or others) should not be treated with herbs. Always see a doctor if your depression is serious (See "Precautions").

Depression

In numerous studies, St. John's wort has been effective in reducing symptoms in those with mild-to-moderate but not severe (or major) depression. In certain studies it appears to work as well as selective serotonin reuptake inhibitors (SSRIs), a popular type of antidepressant that includes fluoxetine (Prozac), citalopram (Celexa), and sertraline (Zoloft) without one of the most common side effects, loss of libido.

St. John's wort contains several chemicals, including hypericin, hyperforin and flavonoids. Researchers aren't exactly sure how St. John's wort works, although it has been suggested that the herb acts like an SSRI, making more serotonin, dopamine and norepinephrine available to the brain. These neurotransmitters help improve one's mood. Scientists thought that hypericin was responsible for these effects, but now they are beginning to think that other chemicals in St. John's wort are the ones that actually have a beneficial effect.

Not all studies agree, however. In one study, St. John's wort was found to be no more effective than placebo for treating depression; however, in the same study, Zoloft also failed to show any benefit in treating depression. A number of other studies have compared St. John's wort to Prozac, Celexa, paroxetine (Paxil), and Zoloft and found that the herb is just as effective as the drug. Other studies are ongoing.

Other Uses

St. John's wort has also shown promise in treating the following conditions, a few of which are related to depression.

• Bacterial and viral infections: In laboratory studies, St. John's wort has demonstrated the ability to fight certain infections, including some bacteria that are resistant to antibiotics. But it isn't known whether St. John's wort would have the same effect in people.
• HIV infection and AIDS: While laboratory research suggests that St. John's wort may kill or slow the growth of human immunodeficiency virus (HIV), St. John's wort interferes with medications used to treat people with the virus. In addition, it appears that the doses of St. John's wort that would be needed are so high that side effects become intolerable. For now, people with HIV or AIDS should not take St. John's wort.
• Premenstrual syndrome (PMS): An early study suggests that St. John's wort may help relieve physical and emotional symptoms of PMS, including cramps, irritability, food cravings, and breast tenderness.
• Seasonal affective disorder (SAD): Used alone, St. John's wort has improved mood in those suffering from SAD (a type of depression that occurs during the winter months because of lack of sunlight). This condition is usually treated with photo (light) therapy. There is some evidence that using St. John's wort together with phototherapy produces even better results.
• Eczema, wounds, minor burns, hemorrhoids: St. John's wort has antibacterial properties and may also help fight inflammation. Applied topically (to the skin), it may relieve symptoms associated with minor wounds and skin irritation.
• Obsessive compulsive disorder, social phobia: St. John's wort has been proposed as a treatment for these conditions, but two preliminary studies in 2005 showed that the herb was not effective in relieving symptoms.

St. John's wort is a shrubby plant with clusters of yellow flowers that have oval, elongate petals. It is believed to be native to Europe, Asia, but is now found throughout the world, often growing alongside the road. The plant gets its name because it is often in full bloom around June 24, the day traditionally celebrated as the birthday of John the Baptist. Both the flowers and leaves are used for medicinal purposes.

The best-studied active components are hypericin and pseudohypericin, found in both the leaves and flowers. Now research suggests, however, that these best-studied components may not be responsible for the plant's medicinal effects. Scientists are now studying St. John's wort's essential oils and flavonoids to see if they have benefits.

St. John's wort can be obtained in many forms: capsules, tablets, tinctures, teas, and oil-based skin lotions. Chopped or powdered forms of the dried herb are also available. Most products are standardized to contain 0.3% hypericin.

Pediatric

The bulk of scientific research on St. John's wort has been conducted in adults. However, one study (more than 100 children under age 12) indicated that St. John's wort may be a safe and effective way of treating mild-to-moderate symptoms of depression in children. Talk to your doctor before giving St. John's wort to a child -- do not give your child a dose without medical supervision. Children being treated with St. John's wort should be carefully monitored for side effects, such as allergic reactions or upset stomach.

Adult

• Dry herb (in capsules or tablets): The usual dose for mild depression and mood disorders is 300 mg (standardized to 0.3% hypericin extract), three times per day, with meals. St. John's wort is available in time-release capsules.
• Liquid extract (1:1): 40 - 60 drops, two times per day.
• Tea: Pour one cup of boiling water over 2 - 4 tsp of dried St. John's wort and steep for 10 minutes. Drink up to 3 cups per day for 4 - 6 weeks.
• Oil or cream: To treat inflammation, as in wounds, burns or hemorrhoids, an oil-based preparation of St. John's wort can be applied topically.

It may take 3 - 4 weeks to feel any effects from St. John's wort.

The use of herbs is a time-honored approach to strengthening the body and treating disease. Herbs, however, can trigger side effects and can interact with other herbs, supplements, or medications. For these reasons, herbs should be taken with care, under the supervision of a health care provider.

St. John's wort is often used to treat depression. If your depression is severe -- causing problems with your daily life or accompanied by thoughts of suicide or of harming yourself or others -- you need to see a doctor immediately. St. John's wort should not be used to treat severe depression.

You should see a doctor to make sure you have the right diagnosis before taking St. John's wort. Your doctor can help you determine the right dose and make sure you are not taking any other medications that might interact with St. John's wort.

Side effects from St. John's wort are generally mild and include stomach upset, hives or other skin rash, fatigue, restlessness, headache, dry mouth, and feelings of dizziness or mental confusion. St. John's wort can also make the skin overly sensitive to sunlight (called photodermatitis). If you have light skin and are taking St. John's wort on a regular basis, be careful about sun exposure. Wear long sleeves and a hat, and use a sunscreen with at least SPF 15 or higher. Avoid sunlamps, tanning booths, and tanning beds.

Because St. John's wort can interact with medications used during surgery, you should stop taking it at least 5 days before surgery. Make sure your doctor and surgeon know you are taking St. John's wort.

Do not take St. John's wort if you have bipolar disorder.

St. John's wort should not be taken by women who are pregnant, trying to become pregnant, or breastfeeding.

St. John's wort interacts with a large number of medications. In most cases, St. John's wort decreases the effectiveness of the medication; in other cases, however, St. John's wort may increase the effects of a medication.

If you are currently being treated with any of the following medications, you should not use St. John's wort without first talking to your doctor:

Antidepressants -- St. John's wort may interact with medications used to treat depression or other mood disorders, including tricyclic antidepressants, SSRIs, and monoamine oxidase inhibitors (MAOIs). Taking St. John's wort with these medications tends to increase side effects, and could potentially lead to a dangerous condition called serotonin syndrome. Do not take St. John's wort with other antidepressants, including:

• SSRIs: Citalopram (Celexa), escitalopram (Lexapro), fluvoxamine (Luvox), paroxetine (Paxil), fluoxetine (Prozac), sertraline (Zoloft)
• Tricyclics: Amitriptyline (Elavil), nortryptyline (Pamelor), imipramine (Tofranil)
• MAOIs: Phenelzine, (Nardil), tranylcypromine (Parnate)
• Nefazodone (Serzone)

Allergy drugs (antihistamines) -- St. John's wort may reduce levels of these drugs in the body, making them less effective:

• Loratadine (Claritin)
• Cetirizine (Zyrtec)
• Fexofenadine (Allegra)

Dextromethorphan (cough medicine) -- When taken at the same time as dextromethorphan, a cough suppressant found in many over-the-counter cough and cold medicines, St. John's wort can increase the risk of side effects, including serotonin syndrome.

Digoxin -- St. John's wort may decrease levels of the medication and reduce its effectiveness. Do not take St. John's wort if you take digoxin.

Drugs that suppress the immune system -- St. John's wort can reduce the effectiveness of these medications, taken after organ transplant or to control autoimmune diseases. In fact, there have been many reports of cyclosporin blood levels dropping in those with a heart or kidney transplant, even leading to rejection of the transplanted organ.

• Adalimumab (Humira)
• Azathioprine (Imuran)
• Cyclosporine
• Etanercept (Enbrel)
• Methotrexate
• Mycophenolate mofetil (CellCept)
• Tacrolimus (Prograf)

Drugs to fight HIV -- St. John's wort appears to interact with at least two kinds of medications used to treat HIV and AIDS: protease inhibitors and non-nucleoside reverse transcriptase inhibitors. The Food and Drug Administration recommends that St. John's wort not be used with any type of antiretroviral medication used to treat HIV or AIDS.

Birth control pills -- There have been reports of breakthrough bleeding in women on birth control pills who were also taking St. John's wort, and it is possible that the herb might interfere with the effectiveness of birth control pills, leading to unplanned pregnancies.

Reserpine -- Based on animal studies, St. John's wort may interfere with reserpine's ability to treat high blood pressure.

Sedatives -- St. John's wort can increase the effect of drugs that have a sedating effect, including:

• Anticonvulsants such as phenytoin (Dilantin) and valproic acid (Depakote)
• Barbiturates
• Benzodiazepines such as alprazolam (Xanax) and diazepam (Valium)
• Drugs to treat insomnia, such as zolpidem (Ambien), zaleplon (Sonata), eszopiclone (Lunesta), and ramelteon (Rozerem)
• Tricyclic antidepressants such as amitriptyline (Elavil)
• Alcohol

Theophylline -- St. John's wort can reduce levels of this medication in the blood. Theophylline is used to open the airways in those suffering from asthma, emphysema, or chronic bronchitis.

Triptans (used to treat migraines) -- St. John's wort can increase the risk of side effects, including serotonin syndrome, when taken with these medications:

• Naratriptan (Amerge)
• Rizatriptan (Maxalt)
• Sumatriptan (Imitrex)
• Zolmitriptan (Zomig)

Warfarin -- St. John's wort reduces the effectiveness of warfarin, an anticoagulant (blood-thinner).

Other drugs -- Because St. John's wort is broken down by certain liver enzymes, it may interact with other drugs that are broken down by the same enzymes. Those drugs may include:

• Antifungal drugs, such as ketoconazole (Nizoral), itraconazole (Sporanox), fluconazole (Diflucan)
• Statins (drugs taken to lower cholesterol)
• Some calcium channel blockers (taken to lower blood pressure)

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