St. John’s Wort
OTHER NAME(S): goatweed, hypericum, Hypericum perforatum, Klamath weed, St. John’s wort (SJW)
Overview
St. John’s wort is a plant called Hypericum perforatum. St. John’s wort dietary supplements are made from the flower of the plant. People most often take St. John’s wort for depression. Common side effects may include dry mouth, headache, upset stomach, sensitivity to sunlight, and tiredness. St. John’s wort can interact with many medicines, even after you stop taking it. Before taking St. John’s wort, make sure to tell your health care provider about any health conditions you have or medicines you are taking.
Uses
What is St. John’s wort used for?
St. John’s wort (Hypericum perforatum) is commonly used for depression. The benefits of St. John’s wort for other uses, such as to help with wound healing, are not well defined.
If you have symptoms of depression, do not try to treat these symptoms on your own. Talk to your health care provider about your treatment options. If you are already taking medicines for depression, talk to your health care provider before starting St. John’s wort. St. John’s wort can cause serious side effects when taken with certain medicines for depression.
The FDA has not reviewed St. John’s wort for safety and effectiveness, and it is not approved by the FDA. Learn more about dietary supplements here.
How does St. John’s wort work (mechanism of action)?
St. John’s wort is a plant called Hypericum perforatum. It is also known by a few other names, including goatweed and Klamath weed. St. John’s wort dietary supplements are made from the flower of the plant.
Hypericins, which are chemicals found in St. John’s wort, have effects on the body. Hypericins can change the levels and effects of certain chemicals in the brain, including serotonin and dopamine. This is similar to how certain medicines work for depression. But it is not clear if St. John’s wort can work as well as antidepressant medicines. When St. John’s wort is used for depression, it may take up to four to six weeks to help with symptoms. This is similar to how long many antidepressant medicines take to help with symptoms.
Herbal products like St. John’s wort naturally contain many different chemicals, including hypericins. The amounts of each chemical in a specific St. John’s wort product may vary. Different amounts of hypericins may change the effects of St. John’s wort on the body. Some St. John’s wort dietary supplements are made to contain a certain amount of hypericins.
How should I store St. John’s wort?
You should store St. John’s wort according to the product label. Most dietary supplements should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.
Side Effects
What are the most common side effects of St. John’s wort?
The most common side effects of St. John’s wort are listed below. These side effects may vary depending on the dose you are taking or the specific product you are using. Tell your health care provider if you have any of these side effects that bother you.
- Dry mouth
- Headache
- Sensitivity to sunlight (see below)
- Sexual problems
- Tiredness
- Upset stomach
There may be other side effects of St. John’s wort that are not listed here. Contact your health care provider if you think you are having a side effect of a supplement. In the U.S., you can report side effects to the FDA at www.safetyreporting.hhs.gov or by calling 888-SAFEFOOD (888-723-3366). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.
What are the serious side effects of St. John’s wort?
While less common, the most serious side effects of St. John’s wort are described below, along with what to do if they happen.
Severe Allergic Reactions. St. John’s wort may cause allergic reactions, which can be serious. Stop taking St. John’s wort and get help right away if you have any of the following symptoms of a serious allergic reaction.
- Breathing problems or wheezing
- Racing heart
- Fever or general ill feeling
- Swollen lymph nodes
- Swelling of the face, lips, mouth, tongue, or throat
- Trouble swallowing or throat tightness
- Itching or skin rash
- Bumps on the skin called hives, which can be red, pink, white, or brown depending on your skin tone
- Nausea or vomiting
- Dizziness, feeling lightheaded, or fainting
- Stomach cramps
- Joint pain
Sensitivity to Sunlight. Your skin may be very sensitive to light from the sun and devices that give off similar light, such as sunlamps and tanning beds, while you are taking St. John’s wort. This is called photosensitivity. This may be more likely to happen in people who have fair skin, who are taking high doses of St. John’s wort, or who apply St. John’s wort to their skin. Use sunscreen and wear a hat and clothes that cover your skin if you need to be in the sunlight. Exposure to this kind of light, even for a short time, can cause your skin to be severely sunburned, blistered, or swollen. Tell your health care provider right away if any of these happen.
Precautions
Who should not use St. John’s wort?
Allergies to Ingredients. People who are allergic to any of the following should not take St. John’s wort.
- Goatweed
- Hypericum perforatum
- Klamath weed
- St. John’s wort (SJW)
- Any of the ingredients in the specific product
Your pharmacist can tell you all of the ingredients in the specific St. John’s wort products they stock.
Drug Interactions. St. John’s wort should not be taken while you are using certain other medicines. Before taking St. John’s wort, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.
What should I know about St. John’s wort before using it?
St. John’s wort is a dietary supplement. It cannot be marketed to treat or cure a disease.
Read and follow the directions on the specific product you are taking, or take it as recommended by your health care provider.
Keep St. John’s wort out of the reach of children.
St. John’s wort may reduce the effects of certain types of birth control. If you use a birth control product that contains hormones, you may need to use a second form of birth control, such as condoms, a diaphragm, or spermicide. Talk to your health care provider about your birth control methods and options.
Herbal products, such as St. John’s wort, naturally contain many different chemicals. The amount of each chemical in a specific St. John’s wort product can change for many reasons, including the area where the plant was grown, the weather during growth, the time of year when it was harvested, and the way the plant was processed after it was harvested. If you switch to a new bottle or a different brand, you may not have the same effects or side effects because of this variability. Talk to your health care provider if you have questions or concerns.
St. John’s wort is available in many different forms, including as a liquid, gummy, or dried ground powder found in capsules or tablets. It is also available as a cream or ointment that can be applied to the skin. Each of these forms may contain different amounts of the chemicals that are naturally found in the plant.
The FDA has not tested St. John’s wort products to confirm that they contain the ingredients stated on their labels. Some dietary supplements have been tested by third-party organizations to confirm that they contain the ingredients listed on their labels and do not contain any harmful chemicals. Learn more about how to choose a safe dietary supplement product here.
What should I tell my health care provider before using St. John's wort?
Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if St. John's wort is right for you.
In particular, make sure that you discuss any of the following.
Current and Past Health Conditions.Before taking St. John’s wort, tell your health care provider if any of the following apply to you.
- You are receiving chemotherapy or radiation.
- You have an upcoming surgery or medical procedure.
Pregnancy. It is not known if or how St. John’s wort could affect pregnancy or harm a fetus. Tell your health care provider if you are pregnant or plan to become pregnant.
Breastfeeding. St. John’s wort may pass into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.
Interactions
Does St. John’s wort interact with foods or drinks?
While taking St. John’s wort, it is best to avoid having large amounts of foods or drinks that contain tyramine. Foods high in tyramine include soy sauce, smoked meats, aged cheeses, sauerkraut, and other pickled foods. Drinks high in tyramine include beer and red wine.
It is unknown if drinking alcohol will affect St. John’s wort, but drinking alcohol while taking St. John’s wort could increase your risk for tiredness.
Does St. John’s wort interact with medicines (drug interactions)?
Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.
In particular, make sure that you discuss if you are using any of the following before taking St. John’s wort.
- A birth control pill, patch, vaginal ring, implant, injection, or intrauterine device (IUD) that contains hormones
- A monoamine oxidase inhibitor (MAOI) within the past two weeks, which is a medicine usually used for depression or Parkinson’s disease
- A selective serotonin reuptake inhibitor (SSRI), such as fluoxetine, paroxetine, or sertraline, which is a medicine commonly used for anxiety and depression
- A serotonin and norepinephrine reuptake inhibitor (SNRI), such as duloxetine or venlafaxine, which is a medicine commonly used for anxiety and depression
- A tricyclic antidepressant, such as amitriptyline, nortriptyline, or protriptyline, even if it is not used for depression
- A medicine that makes you more sensitive to sunlight
St. John’s wort may alter the blood levels of many medicines. This effect may last for up to two weeks after stopping St. John’s wort. Tell your health care provider about all medicines that you take or have recently taken.
The interactions between St. John’s wort and medicines are not fully understood. As with most dietary supplements, the research on drug interactions with St. John’s wort is incomplete. Always check with your health care provider before using St. John's wort with any medicines.
Dosing
What should I do if I accidentally use too much St. John’s wort?
If you or someone else has used too much St. John's wort, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.
St. John’s wort dietary supplements are available in many different doses. These supplements can have serious interactions with many medicines. Speak with a health care provider about how to use St. John’s wort safely. Do not take double or extra doses, even if you miss a dose.
References
- The American Association of Pharmaceutical Scientists Journal: “Herb-drug interactions with St John’s Wort (Hypericum perforatum): an update on clinical observations.”
- Cochrane: “St John’s wort for major depression (review).”
- Cureus: “Advantages and disadvantages of using St. John’s wort as a treatment for depression.”
- Drugs and Lactation Database (LactMed) [Internet]: “St. John’s wort.”
- Memorial Sloan Kettering Cancer Center: “St. John’s wort.”
- National Center for Complementary and Integrative Health: “St. John’s Wort,” “St. John’s Wort and Depression: In Depth,” “Depression and Complementary Health Approaches: What the Science Says.”