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St. John's Wort Side Effects: Sun, Stomach, Sleep
St. John's wort side effects most often include headache, nausea, dry mouth, sleepiness, stomach upset and a stronger reaction to sunlight (MSK, St. John's Wort). The bigger risk is how it changes other medicines. If a capsule disagrees with you, stop it and call a clinician.
Written by the MemoPryl label deskUpdated · 4 min read
What are the common St. John's wort side effects?
The common ones are mild: headache, nausea, dry mouth, sleepiness, stomach upset and sun sensitivity (MSK, St. John's Wort).
Most people who report trouble describe a stomach that feels off or a day that feels slow. Some notice restless sleep instead.
| Effect | What it can feel like |
|---|---|
| Headache | A dull ache that starts after a few doses |
| Nausea or stomach upset | Queasy feeling, often on an empty stomach |
| Dry mouth | Thirst and a sticky feeling |
| Sleepiness | Drowsy in the daytime |
| Sun sensitivity | Skin burns or reddens faster than usual |
Why does St. John's wort make skin burn faster?
Because the herb can make skin more sensitive to light. NCCIH says large oral doses may cause severe skin reactions after sun exposure (NCCIH, St. John's Wort safety).
If a capsule lists it, treat sunny days with care. Cover up, use shade and ask a pharmacist whether any other medicine you take also adds to sun sensitivity.
Next step: if you get a rash, blisters or a burn that seems out of proportion to the time outdoors, stop the capsule and call a clinician.
Which St. John's wort side effects need a call right away?
Signs of serotonin syndrome need a call right away. They include agitation, diarrhea, a fast heartbeat, hallucinations and a high body temperature (MedlinePlus, Serotonin syndrome).
The risk rises when the herb is combined with antidepressants or other medicines that raise serotonin. It can appear within minutes to hours, and untreated it can be deadly.
Do not stop a prescribed medicine on your own. Call your provider and describe what you take, including supplements. For medicines that can clash, see the pharmacist guide.
Ask your doctor or pharmacist before you start any capsule that lists St. John's wort.
MemoPryl: capsules in 2, 3 or 6 bottlesRead the bottle · check your medicines · 60-day window (confirm)
See packsWhat does this mean for a MemoPryl buyer?
It means you should check the bottle before the first capsule. St. John's wort is one of six names tied to MemoPryl through a sibling pack, and that link is unconfirmed for your bottle.
No warnings text, directions or amounts are printed on any image we hold. Two bottle photos also disagree on capsule count. Read the panel that arrives, and look for the herb by name.
If the panel lists it and you take any regular medicine, call a pharmacist first. Details on the other five names are on the ingredients page.
Thinking about MemoPryl?Check your medicines with a pharmacist first. Prices and the 60-day window are confirmed at checkout.
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How do I report a bad reaction?
Stop the product, get medical advice, then report it. FDA runs a Safety Reporting Portal for serious reactions (FDA, Report a Supplement Problem).
Keep the bottle, note the lot number and write down the date of each capsule. Those details help a clinician and help the report.
FAQ01
MemoPryl questions people ask
Does St. John's wort cause weight gain?
Weight gain is not among the side effects in the sources we cite. Changes in appetite can follow a shift in mood or other medicines. If your weight moves and you take the herb, mention both to a clinician.
Can St. John's wort make you sleepy?
Yes. Sleepiness is a listed side effect (MSK, St. John's Wort). Take care driving until you know how a capsule affects you, and tell your pharmacist about any other sedating medicine.
How long do St. John's wort side effects last?
No source we cite gives a fixed time. Mild effects often ease when the capsule is stopped. If symptoms persist or feel severe, call a clinician rather than waiting.
Who wrote this02
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Pages built from the bottle images, the seller's product notes and linked NIH, FDA, FTC and peer-reviewed sources.
Last updated . Learn about our editorial standards and how we check reviews. This website is run by Official stocking desk for MemoPryl, not by the manufacturer or the distributor of the bottle. We make money when you buy through our order links.
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