• Basic Info
• Top Questions
• Interactions

Tradition

WARNING: DISCLAIMER: The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

Dosing

Adults (18 years and older)

Clinical trials have used a range of doses, including 0.17-2.7 milligrams of hypericin by mouth, and 900-1,800 milligrams of St. John's wort extract daily by mouth.

1.5% hyperforin (verum) has been applied to the skin for treatment of atopic dermatitis.

Children (younger than 18 years)

There is not enough scientific data to recommend St. John's wort in children.

Safety

DISCLAIMER: Many complementary techniques are practiced by healthcare professionals with formal training, in accordance with the standards of national organizations. However, this is not universally the case, and adverse effects are possible. Due to limited research, in some cases only limited safety information is available.

Allergies

Infrequent allergic skin reactions, including rash and itching, are reported in human studies.

Side Effects and Warnings

In published studies, St. John's wort has generally been well tolerated at recommended doses for up to 1-3 months. The most common adverse effects include gastrointestinal upset, skin reactions, fatigue/sedation, restlessness or anxiety, sexual dysfunction (including impotence), dizziness, headache, and dry mouth. Several recent studies suggest that side effects occur in one to three percent of patients taking St. John's wort, and that the number of adverse events may be similar to placebo (and less than standard antidepressant drugs). Animal toxicity studies have found only non-specific symptoms such as weight loss. One small study reported elevated thyroid stimulating hormone (TSH) levels to be associated with taking St. John's wort.

It has been reported that St. John's wort may cause psychiatric symptoms such as suicidal and homicidal thoughts.

Delayed ejaculation has been reported in animal studies.

Pregnancy & Breastfeeding

There is insufficient data available at this time to recommend use during pregnancy or breastfeeding.

Interactions

Interactions with Drugs

St. John's wort interferes with the way the body processes many drugs using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be increased in the blood in the short-term (causing increased effects or potentially serious adverse reactions), and/or decreased in the blood in the long-term (which can reduce the intended effects). Examples of medications that may be affected by St. John's wort in this manner include carbamazepine, cyclosporin, irinotecan, midazolam, nifedipine, birth control pills, simvastatin, theophylline, tricyclic antidepressants, warfarin, or HIV drugs such as non-nucleoside reverse transcriptase inhibitors (NNRTIs) or protease inhibitors (PIs). The U.S. Food & Drug Administration suggests that patients with HIV/AIDS on protease inhibitors or non-nucleoside reverse transcriptase inhibitors avoid taking St. John's wort.

Case reports exist of significant reductions in cyclosporine, tacrolimus, and mycophenolic acid drug levels, and possible organ rejections in people with transplants who are taking St. John's wort. Reports also exist of altered menstrual flow, bleeding, and unwanted pregnancies in women taking birth control pills and St. John's wort at the same time. St. John's wort may interact with digoxin or digitoxin, resulting in a decrease in digoxin blood concentration. In general, individuals should check the package insert and speak with a qualified healthcare professional including a pharmacist about possible interactions with St. John's wort.

Taking St. John's wort with other antidepressants may lead to increased side effects, including serotonin syndrome and mania. Serotonin syndrome is a condition defined by muscle rigidity, fever, confusion, increased blood pressure and heart rate, and coma. Mania is defined by symptoms of elevated or irritable mood, rapid speech or thoughts, increased activity, and decreased need for sleep. These interactions may occur in people taking St. John's wort with SSRI antidepressants such as fluoxetine (Prozac®) or sertraline (Zoloft®), or with monoamine oxidase inhibitors (MAOIs) such as isocarboxazid (Marplan®), phenelzine (Nardil®), or tranylcypromine (Parnate®). Using St. John's wort with MAOIs may also increase the risk of severely increased blood pressure.

St. John's wort may lead to increased risk of sun sensitivity when taken with other drugs such as antibiotics or birth control pills. St. John's wort may interact with anesthetic drugs. A possible interaction with loperamide (Imodium®) has been reported; confusion and agitation occurred in one patient taking St. John's wort, loperamide, and the herb valerian (Valeriana officinalis). St. John's wort may interact with triptan-type headache medications. Examples include naratriptan (Amerge®), rizatriptan (Maxalt®), sumatriptan (Imitrex®), and zolmitriptan (Zomig®). In theory, St. John's wort may also interact with certain chemotherapy drugs such as anthracyclines. St. John's wort may increase anti-inflammatory effects of COX2 inhibitor drugs like Vioxx®, or NSAIDS like ibuprofen (Motrin®).

St John's wort may increase imatinib clearance. Thus patients taking imatinib should avoid taking St John's wort. Concomitant use of enzyme inducers, including St John's wort, may necessitate an increase in the imatinib dose to maintain effectiveness.

In higher doses, St. John's wort has been shown to decrease the blood concentrations of omeprazole, tolbutamide, caffeine, dextromethorphan, fexofenadine, carbamazepine, and cimetidine, among other medications. No relevant interaction has been seen with alprazolam, caffeine, tolbutamide, and digoxin by treatment with a low-hyperforin St. John's wort extract.

Coadministration of St. John's wort leads to a short-term but clinically irrelevant increase followed by a prolonged extensive reduction in voriconazole exposure. St. John's wort might put certain individuals at highest risk for potential voriconazole treatment failure.

Although cases of interaction are rare, caution is advised when taking St. John's wort and coumarin-type anticoagulants.

Caution is also advised when taking benzodiazepine tranquilizers, opioids or P-glycoprotein regulated drugs. In general, individuals should check the package insert and speak with a qualified healthcare professional including a pharmacist about possible interactions with St. John's wort.

Interactions with Herbs & Dietary Supplements

St. John's wort may interfere with the way the body processes certain herbs and supplements using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be increased in the blood in the short-term, causing increased effects or potentially serious adverse reactions, or decreased in the blood in the long-term, which can reduce the intended effects.

Taking St. John's wort with herbs or supplements with antidepressant activity may lead to increased side effects, including serotonin syndrome, mania, or severe increase in blood pressure. There is a particular risk of these interactions occurring with agents that possess possible monoamine oxidase inhibitory properties.

St. John's wort may lead to increased risk of sun sensitivity when taken with capsaicin or other photosensitizing products. St. John's wort may interact with herbs that also possess cardiac glycoside properties and decrease blood levels.

A possible interaction with the herb valerian (Valeriana officinalis) has been reported: confusion and agitation occurred in one patient taking St. John's wort, loperamide (Immodium®) and valerian. However, St. John's wort and valerian are often used together, with few reported of adverse events. In theory, due to the presence of tannins, St. John's wort may inhibit the absorption of iron.

Although cases of interaction are rare, caution is advised when taking St. John's wort and coumarin-type anticoagulants.

Caution is also advised when taking red yeast rice or any herb or supplements that is P-glycoprotein regulated. In general, individuals should speak with a qualified healthcare professional including a pharmacist about possible interactions with St. John's wort.