{"ok":true,"entry":{"slug":"st-johns-wort","kind":"supplement","name":"St John's wort","aliases":["Hypericum perforatum"],"brands_sg":["California Gold Nutrition","Swanson Vitamins","Nature's Way","Nature's Answer","Nutricost"],"class":"botanical","tags":["general"],"use_for":"sold for mood · may help mild or moderate depression","use_after":null,"use_duration":null,"take_with":null,"pros":["nccih: beats placebo for mild or moderate depression","matches standard antidepressants in those trials","up to 12 weeks looks safe if on no other medicine"],"cons":["weakens many medicines, sometimes dangerously","hsa annex b: warfarin, digoxin, the pill, ssris","large doses: severe skin reactions after sun"],"dose_note":"nccih states no dose; its safety statements are framed by duration — safe for most adults not taking medicines for up to 12 weeks, with some studies indicating a year or more. no rda, ul or fda daily value exists, and hsa's tables 4–5 cover vitamins and minerals only, so no sg daily maximum applies","dosage":{"ul":null,"unit":"mg","fda_dv":null,"rda_ai":null,"ul_status":"none_established","population":"general adult","hsa_max_daily":null},"ul_status":"none_established","sg_class":null,"cautions":["on any prescription medicine — nccih reports life-threatening interactions","pregnancy — may increase the risk of birth defects","breastfeeding — colic, drowsiness and lethargy reported in infants","singapore: an hsa annex b ingredient; ad and sales-promotion permits apply"],"clashes":[{"src":["nccih_sjw_serotonin","hsa_pr_annexb"],"note":"nccih: may lead to increased serotonin-related side effects, which can be serious","with":"antidepressants and other serotonin drugs"},{"src":["nccih_sjw_interactions","hsa_pr_annexb"],"note":"nccih: st john's wort can weaken the effect","with":"birth control pills"},{"src":["nccih_sjw_interactions","hsa_pr_annexb"],"note":"nccih and hsa both list it as weakened","with":"warfarin (a blood thinner)"},{"src":["nccih_sjw_interactions","hsa_pr_annexb"],"note":"nccih: phenytoin and carbamazepine among the medicines weakened","with":"digoxin, ivabradine and anticonvulsants"},{"src":["nccih_sjw_interactions"],"note":"nccih: effects weakened, including for transplant and hiv drugs","with":"cyclosporine, hiv and cancer medicines"}],"sources":[{"id":"nccih_sjw","url":"https://www.nccih.nih.gov/health/st-johns-wort","label":"NIH NCCIH — St. John's Wort, how much do we know","quote":"results indicate that it may be helpful for mild or moderate depression … It has been clearly shown that St. John's wort can interact in dangerous, sometimes life-threatening ways with a variety of medicines.","accessed":"2026-08-27"},{"id":"nccih_sjw_evidence","url":"https://www.nccih.nih.gov/health/st-johns-wort","label":"NIH NCCIH — St. John's Wort, what have we learned","quote":"appears to be more effective than a placebo … and as effective as standard antidepressant medications for mild or moderate depression. It's uncertain whether this is true for severe depression or for time periods longer than 12 weeks.","accessed":"2026-08-27"},{"id":"nccih_sjw_safety","url":"https://www.nccih.nih.gov/health/st-johns-wort","label":"NIH NCCIH — St. John's Wort, what do we know about safety","quote":"For most adults who are not taking any kind of medicine, St. John's wort appears to be safe when used for up to 12 weeks … might cause severe skin reactions after sun exposure.","accessed":"2026-08-27"},{"id":"nccih_sjw_interactions","url":"https://www.nccih.nih.gov/health/st-johns-wort","label":"NIH NCCIH — St. John's Wort, list of medicines whose effects it weakens","quote":"St. John's wort can weaken the effects of many medicines … Birth control pills … Cyclosporine … Some drugs used to prevent seizures, including phenytoin and carbamazepine … Some heart medications, including digoxin and ivabradine … Warfarin","accessed":"2026-08-27"},{"id":"nccih_sjw_serotonin","url":"https://www.nccih.nih.gov/health/st-johns-wort","label":"NIH NCCIH — St. John's Wort, serotonin-related side effects","quote":"taking St. John's wort with certain antidepressants or other drugs that affect serotonin … may lead to increased serotonin-related side effects, which can be serious.","accessed":"2026-08-27"},{"id":"nccih_sjw_pregnancy","url":"https://www.nccih.nih.gov/health/st-johns-wort","label":"NIH NCCIH — St. John's Wort, pregnancy and breastfeeding","quote":"It may be unsafe to use St. John's wort during pregnancy because it may increase the risk of birth defects. Breastfeeding infants of mothers who take St. John's wort can experience colic, drowsiness, and lethargy.","accessed":"2026-08-27"},{"id":"hsa_pr_annexb","url":"https://file.go.gov.sg/hsa-chp-prohibited-restricted-ing-guidelines.pdf","label":"HSA — Guidelines on Prohibited and Restricted Ingredients in HS and TM (Oct 2025), Annex B (substances with potential safety issues), row 3: Hypericum perforatum (St John's wort)","quote":"Hypericum perforatum affects the metabolism of some medicines thus reducing the medicines' therapeutic effects, e.g. warfarin, digoxin, oral contraceptives, anticonvulsants, SSRIs, etc. … Caution consumers to consult doctor prior to use of product if they are on medication.","accessed":"2026-08-27"},{"id":"hsa_hs_advert","url":"https://file.go.gov.sg/hsa-hs-guidelines.pdf","label":"HSA Singapore — Health Supplements Guidelines (January 2026), clause 7.1, medical advertisement and sales promotion permit control","quote":"Some types of HS are subject to medical advertisements and sales promotion permit control. These include Quasi-Medicinal (QM) vitamins and/or mineral HS, as well as some other HS (e.g. St John's wort, melatonin products).","accessed":"2026-08-27"},{"id":"hsa_hs_limits","url":"https://file.go.gov.sg/hsa-hs-guidelines.pdf","label":"HSA Singapore — Health Supplements Guidelines (January 2026), clause 4.8 and Tables 4–5 (vitamins and minerals only)","quote":"HS for use by the general adult population should not contain vitamins and minerals exceeding the stipulated limits stated in Tables 4 and 5.","accessed":"2026-08-27"},{"id":"iherb_sg","url":"https://sg.iherb.com/c/st-johns-wort","label":"iHerb Singapore — Supplements > Herbs > St. John's Wort category page, default order (1 - 43 of 43 results); first 5 distinct brands: California Gold Nutrition, Swanson Vitamins, Nature's Way, Nature's Answer, Nutricost","quote":"California Gold Nutrition, EuroHerbs™, St. John's Wort Extract … Swanson Vitamins, Full Spectrum® St. John's Wort, 375 mg … Nature's Way, St. John's Wort … Nature's Answer, St. John's Wort Extract … Nutricost, St. John's Wort, 500 mg","accessed":"2026-08-27"}],"brand_certs":null,"updated_at":"2026-08-29T16:16:31.341231+08:00"},"disclaimer":"kozen-x is not a medical device and does not give medical advice. it lists what published sources have written down. absence of a record is not the same as safe."}