Hypericum side effects

The short version: St. John's wort has real side effects, but the evidence here shows it is generally better tolerated than prescription antidepressants, with the main risks being drug interactions and photosensitivity.

The evidence you asked about comes from clinical trials and reviews, not from manufacturer-funded studies. A 2001 trial comparing St. John's wort extract Ze 117 to fluoxetine (Prozac) in 240 people with mild-to-moderate depression found fewer side effects with the herb: 14% of people on St. John's wort reported adverse events versus 25% on fluoxetine [1]. A larger 2002 placebo-controlled trial of 375 people using extract WS 5570 found the opposite pattern — 30.6% of the St. John's wort group reported side effects versus 37% on placebo, meaning the herb group actually had fewer complaints than people taking a sugar pill [3]. The most common side effects reported were nausea, headache, dizziness, and abdominal pain, each affecting roughly 2-5% of people [3].

The real concern is not the direct side effects but the drug interactions. St. John's wort strongly induces liver enzymes called CYP3A4 and P-glycoprotein transporters, meaning it speeds up how your body breaks down many medications [5]. This can make birth control pills, blood thinners like warfarin, heart medications like digoxin, and immunosuppressants less effective [5]. The evidence recommends stopping St. John's wort at least 5 days before surgery because of these interactions [5]. There is also a risk of photosensitivity — increased sensitivity to sunlight — due to the compound hypericin [5]. A small study on 16 volunteers found that topical St. John's wort oil increased skin redness after UV exposure, though it did not change the minimum dose needed to cause sunburn [4].

The evidence here does not include long-term safety data beyond 6 weeks of use. The trials are short and the meta-analysis on menopausal symptoms found no significant difference in overall adverse event rates compared to placebo, but the confidence intervals were wide [2]. For most people, the direct side effects of St. John's wort are mild and less common than with standard antidepressants. The real risk is taking it alongside other medications without knowing about the enzyme induction.

My call: St. John's wort has a favorable short-term safety profile compared to prescription antidepressants, but the drug interaction risk is serious and well-documented. Confidence: moderate — the short-term data is solid, but long-term safety beyond 6 weeks is not covered by these records.