St. John’s Wort Side Effects, Uses, Benefits & Interactions

by jamespereiramadsa
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By Dr. Joseph Mercola,

St. John's wort (Hypericum perforatum) is named after St. John the Baptist, since it's usually in full bloom by June 24, the saint's feast day.1 The plant bears yellow flowers2 with oblong petals3 that have black dots on their edges. It can stand 1 to 3 feet tall, and has multiple reddish stems4 and yellow-green leaves.5 Although primarily found in Europe, St. John's wort can now be found growing in the U.S.,6 China, northern Africa, western7 and eastern Asia, Australia and New Zealand.8

The plant typically blooms during summertime, and can be seen growing in woods, hedges, roadsides, pastures and meadows.9 St. John's wort also bears sticky fruits with three-chambered capsules10 that hold multiple small, black and pepper-like seeds11 with a resinous smell.12

Important Benefits of St. John's Wort

Under certain conditions, St. John's wort may be helpful for your mental health if you're feeling depressed — provided you aren't currently taking prescription antidepressants, as the combination of the two could cause serious increases in your serotonin levels.13

Used alone and under the supervision of your health care provider, the herb contains compounds such as hypericin, hyperforin, flavonoids and flavonoid derivatives, xanthone derivatives, amentoflavone, biapigenin and volatile oils that may help combat depression.14,15

An analysis of 35 studies published in Systematic Reviews in 2016 revealed that St. John's wort assisted in alleviating depression symptoms better than a placebo, and similarly to typical conventional drugs.16

Authors of a 1997 Pharmacopsychiatry animal study discovered that St. John's wort extract may work like antidepressants by helping prevent reuptake of the neurotransmitters serotonin, dopamine and norepinephrine, and promoting positive effects in mice who were given the substance.17

This herb may also help address mental health problems such as anxiety or seasonal affective disorder (SAD),18 which normally occurs during the winter months because of a lack of sunlight.19Aside from impacts toward your mental health, St. John's wort may also help:

  • Deliver antioxidant and anti-inflammatory capabilities — This herb's flavonoid and phenolic acid content may promote antioxidant abilities.20 It also has anti-inflammatory properties that may be useful in combating depressive disorders21 or joint-related problems.22
  • Ease premenstrual syndrome (PMS) — Women experiencing typical PMS symptoms like cramps, irritability, food cravings, breast tenderness and other physical and emotional indicators may benefit from using this herb.23
  • Alleviate multiple problems prevalent during menopause24 In this 1999 Advances in Therapy article, menopausal women who took a St. John's wort tablet three times a day for 12 weeks had substantial improvements in psychological and psychosomatic indicators.25 Another study, which was published in the journal Menopause in 2010, revealed that St. John's wort helped reduce frequency of hot flashes among perimenopausal or postmenopausal women.26
  • Provide relief against hemorrhoids — According to the book "Herbal Healing for Women," enlarged and painful hemorrhoids can be targeted by applying a comfrey and St. John's wort poultice, a paste made from fresh or dried herbs wrapped in a cheesecloth, on the area.27
  • Lower risk of breast cancer — Study authors of this 2018 International Journal of Molecular Sciences article claimed that St. John's wort extract helped prevent cancer cell growth and promoted cell death or apoptosis.28
  • Inhibit alcoholism — In an animal study, rats that were bred specifically to prefer alcohol were given St. John's wort extract orally. The researchers found that the rats given the extract ingested 50% less alcohol than the rats that were not given St. John's wort.29,30
  • Address chronic fatigue syndrome (CFS) — Results of a 2002 Indian Journal of Experimental Biology animal study noted that St. John's wort herbal products may be beneficial in combating this health problem by restoring the lipid peroxidation and glutathione levels of the test subjects.31

What Are St. John's Wort's Uses?

St. John's wort was used to treat wounded soldiers during the Crusades,32 and drive out the "inner devil" in people during Medieval times. However, St. John's wort's history of medicinal use dates back to ancient Greece, where it was believed to possess "magical powers."33 It was also recommended to be used against hallucinations34 by Paracelsus, a Swiss man considered "the father of chemistry and the reformer of material medica" (among many other nicknames).35

The use of St. John's wort is prevalent in some European countries, such as Germany, against mental health issues like depression.36 St. John's wort can be found in other forms such as tinctures, oils or balms that may help promote healing of burns, wounds, insect bites and bruises.37,38 You may also encounter St. John's wort products such as supplements,39 liquids, powders40 and teas.41,42

Give St. John's Wort Tea a Try

St. John's wort leaves and flowers can be used to make tea43 that may assist in:44

  • Boosting your mood, relieve tension45 and alleviating depression and anxiety
  • Providing relief against neuralgia
  • Alleviating insomnia
  • Lessening physical pain caused by localized nerve pains
  • Combating inflammation linked to strains and sprains, such as tennis elbow
  • Tackling urinary problems like incontinence and bedwetting in children46
  • Alleviating gallbladder issues47
  • Addressing menstrual cramps48
  • Removing mucus from the lungs, stomach, kidneys and bladder49

Remember that if you have high blood pressure levels, are taking antihypertensive50 or antidepressant medications, or would need to undergo surgery, drinking St. John's wort tea may lead to adverse effects.51 Also, do not take St. John's wort without consulting a health care practitioner if you are on prescription medications of any sort including birth control pills.52

How St. John's Wort Oil Can Boost Your Health

Are you interested in trying St. John's wort oil? Initial research has revealed that it possesses anti-inflammatory capabilities,53 and may help:

  • Alleviate wounds and burns — Authors of a 2014 Planta Medica article noted that when used topically, St. John's wort oil or tinctures may help relieve minor wounds and burns, sunburn, abrasions, bruises, contusions, ulcers and myalgia.54 It's also possible to use this oil to help relieve cold sores and viral skin lesions.
  • Combat inflammatory skin conditions — If you're diagnosed with either eczema, psoriasis or lupus, carefully and neatly applying St. John's wort oil on the affected area may promote a soothing sensation.55
  • Control oily skin — Using infused St. John's wort oil may help you combat naturally oily skin.56
  • Relieve muscle and joint pain and inflammation — Rubbing a few drops of St. John's wort oil onto sore muscles may help alleviate discomfort caused by conditions like sciatica, low back pain, neuralgia, arthritis, rheumatic pains,57 tendonitis or nerve pain.58

If you plan on using this oil, consult a physician and take an allergen patch test to check for potential side effects. Dilute the essential oil with a carrier oil like sweet almond, olive, jojoba or coconut, or add it to other oil blends, since it can deliver a warm, balsamic, herbaceous and sweet scent. St. John's wort oil blends well with clary sage, cedar,59 lavender and lemon balm oils.60

Side Effects of St. John's Wort

No matter what form of St. John's wort you use, remember that it may lead to photosensitivity61 or sun sensitivity.62 If you're using St. John's wort, try to avoid the sun as much as possible, or use sunscreen or wear protective clothing.63 Some of the other side effects linked to St. John's wort include:64,65

  • Anxiety
  • Restlessness
  • Tiredness or fatigue
  • Sedation
  • Dizziness
  • Headaches
  • Sexual dysfunction
  • Skin reactions
  • Stomach upset
  • Dry mouth
  • Diarrhea
  • Insomnia
  • Irritability
  • Hypoglycemia (low blood sugar levels)

As mentioned, St. John's wort has the tendency to interact with multiple drugs, as highlighted by PennState's Milton S. Hershey Medical Center:

  • HIV/AIDS drugs such as protease inhibitors and non-nucleoside reverse transcriptase inhibitors
  • Antifungal drugs
  • Statins or cholesterol-lowering drugs such as atorvastatin (Lipitor), lovastatin (Mevacor) and simvastatin (Zocor)
  • Certain calcium channel blockers
  • Any medicine broken down by the liver

If you're taking these drugs, refrain from using St. John's wort with them since it may lead to other health issues. This herb can also reduce the drugs' effectiveness.66

Before using St. John's wort, talk to a physician67 or mental health professional (if you're struggling with a mental health problem) to determine if this will be beneficial for your condition and find out the ideal dosage you may need to take. If you're pregnant or breastfeeding, avoid using any form of St. John's wort,68 since it may cause your baby to develop drowsiness, fussiness or colic.69


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