St. John's Wort Side Effects: What You Need to Know Before Taking It

When people look for natural ways to feel better, St. John's Wort, a herbal supplement made from the plant Hypericum perforatum, often used for mild depression and anxiety. Also known as hypericum, it’s sold in capsules, teas, and tinctures—but it’s not harmless just because it’s natural. Many think herbal means safe, but St. John's Wort can change how your body handles other medicines in ways you won’t expect.

One of the biggest dangers is how it interacts with common drugs. If you’re on birth control, it might stop working. If you take antidepressants like SSRIs or SNRIs, you could risk serotonin syndrome, a dangerous condition caused by too much serotonin in the brain, leading to rapid heart rate, high blood pressure, and confusion. Even over-the-counter painkillers or blood thinners can become risky when mixed with it. This isn’t theoretical—doctors and pharmacists see real cases every year where people ended up in the ER because they didn’t know this herb acted like a drug.

Side effects aren’t always obvious either. Some people get dizzy, dry mouth, or upset stomach. Others notice increased sensitivity to sunlight—something you might not connect to the supplement until you get a bad sunburn in early spring. Sleep problems, agitation, and even sexual side effects are reported. And if you’re planning surgery, stopping it weeks ahead is critical, because it can interfere with anesthesia.

It’s not just about what it does to your body—it’s about what it does to your other treatments. If you’re managing anxiety with Lexapro, or depression with venlafaxine, or even taking warfarin for blood clots, St. John’s Wort can turn those meds into something unpredictable. That’s why pharmacists warn against mixing it with any prescription, even if your doctor didn’t mention it.

There’s a reason you see articles here about NTI generics, drug interactions, and counterfeit meds—because what you put in your body matters. St. John’s Wort isn’t a harmless tea. It’s a powerful plant extract that acts like a drug, and it deserves the same caution as any prescription. You wouldn’t swap your heart medication without talking to your doctor. Don’t do it with this herb either.

Below, you’ll find real comparisons and warnings from people who’ve been there—whether it’s how St. John’s Wort clashes with antidepressants like venlafaxine, what to do if you’re switching from it to a prescription, or why some people feel worse after starting it. These aren’t theories. They’re experiences that can help you avoid the same mistakes.