Safety
St. John's Wort Drug Interactions: What MemoPryl Buyers Should Check First
St. John's wort, one of MemoPryl's named ingredients, can weaken many medicines and interact in dangerous, sometimes life-threatening ways (NCCIH, St. John's wort). Birth control pills, warfarin, some antidepressants, some statins, and heart, HIV, transplant, seizure and cancer drugs are on the list. MemoPryl's amount is not public and its bottle shows no warning, so a pharmacist check comes before the first capsule.
Written by the MemoPryl editorial teamUpdated · 9 min read
The basics
What does St. John's wort do to other medicines?
It can make them work less well, and with a few drugs it can cause harm. The National Center for Complementary and Integrative Health (NCCIH) says the herb interacts with many medicines "in dangerous, sometimes life-threatening ways" (NCCIH, St. John's wort).
St. John's wort (Hypericum perforatum) is studied mainly for mild to moderate depression. The NCCIH source gives no evidence that it helps memory.
For adults on no medicines, it appears safe for up to 12 weeks. The trouble starts when it meets a prescription.
Interaction list
Which medicines interact with St. John's wort? A table by drug type
Nine groups appear on the NCCIH list. "Some" means not every drug in a group is affected.
| Drug type | Named in the source | What can go wrong |
|---|---|---|
| Antidepressants | Some antidepressants | Serotonin side effects, which can be serious |
| Birth control | Birth control pills | Weaker protection against pregnancy |
| Transplant drugs | Cyclosporine | The drug may work less well |
| Seizure drugs | Phenytoin, carbamazepine and some others | Weaker seizure control |
| Heart drugs | Digoxin, ivabradine | The drug may work less well |
| HIV drugs | Some HIV medicines | Weaker effect |
| Cancer drugs | Some cancer medicines | Weaker effect |
| Blood thinner | Warfarin | Weaker effect on clotting |
| Cholesterol drugs | Some statins | The drug may work less well |
Thyroid medicine and beta blockers are not on the NCCIH list. Missing from one list is not a safety pass.
Antidepressants
Can St. John's wort cause serotonin side effects with antidepressants?
Yes. Combined with some antidepressants, St. John's wort can cause serotonin side effects, one of the serious interactions on the NCCIH list.
People often search for sertraline or Lexapro by name. The source says "some antidepressants" without listing brands, so ask the prescriber who chose yours.
A memory capsule does not look like a mood product. The front of a MemoPryl bottle never mentions the herb, so a buyer may not connect the two.
Keep taking your prescribed medicine. Never stop or change a dose on your own to make room for a supplement. Leave the supplement out and ask first.
Birth control
Can St. John's wort make birth control less effective?
Yes. NCCIH names birth control pills among the medicines St. John's wort can weaken. A weaker pill gives less protection against pregnancy.
The MemoPryl brand graphic says only "Adults, 18+", so young adults on the pill can buy it. Talk to the prescriber first, and ask whether a backup method makes sense.
Side effects
Does St. John's wort cause sun sensitivity or other side effects?
It can. NCCIH links large doses of St. John's wort to sun sensitivity, so your skin may react more to sunlight.
Nobody outside the maker knows whether MemoPryl reaches a large dose, because its amounts are not public. If your skin reacts more than usual, stop the capsules and call your doctor.
Other effects reported for the herb:
- Diarrhea
- Dizziness
- Trouble sleeping
- Restlessness
- Skin tingling
The MemoPryl side effects guide covers every ingredient.
Pregnancy
Is St. John's wort safe in pregnancy or while breastfeeding?
It may not be. NCCIH says St. John's wort may be unsafe during pregnancy, and breastfed babies may develop colic or drowsiness (NCCIH, St. John's wort). Ginkgo, also in MemoPryl, may be unsafe in pregnancy too (NCCIH, Ginkgo).
Skip it
Two ingredients carry pregnancy cautions, and no amounts are printed.
Think of the baby
Colic and drowsiness are the effects reported in nursing infants.
Check the pill
If you rely on the pill until you are ready, the herb can weaken it.
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Why does a memory supplement with St. John's wort deserve a pharmacist check?
Because the label gives a pharmacist little to work with. We have seen no Supplement Facts panel, no amounts and no warning text for either MemoPryl version.
- St. John's wort is not there for memory. Its research is about mood.
- The eBay seller also lists huperzine A, which works much like prescription Alzheimer's drugs and may slow the heart rate (ADDF, Huperzine A).
- A second product with St. John's wort would double up.
To be fair, the brand names the herb openly on its ingredient graphic. The St. John's wort ingredient page reviews the evidence.
At the counter
What should you ask your pharmacist about MemoPryl?
Bring the bottle and your list
List every prescription, over-the-counter medicine and supplement you use, birth control included.
Name each medicine
Ask, "Does St. John's wort affect this one?" for each drug, rather than asking in general.
Ask about the label version
The eBay seller lists huperzine A and alpha-GPC too. See the label versions guide.
Ask what to watch for
If you get the go-ahead, ask which changes mean stop and call.
Ask about timing
Our sources do not say how long the herb affects other drugs after the last dose. Ask before you start or switch any medicine.
Emergency
When should you call 911?
Sudden numbness or weakness on one side of the body, sudden confusion, trouble speaking, seeing or walking, or a sudden severe headache. These can be signs of a stroke (CDC, Stroke signs).
Do not wait to work out whether a supplement is to blame.
Bottom line
What is the bottom line on St. John's wort and MemoPryl?
St. John's wort turns MemoPryl into a medicine question. On no prescriptions, the herb's short-term safety record is reasonable. On anything at all, check first.
Supplements reach shelves without FDA approval (FDA, Supplement Q&A), so this check falls to you and your pharmacist. A sealed bottle can wait while you get an answer.
Sources
- St. John's Wort: Usefulness and Safety. National Center for Complementary and Integrative Health, 2026.Studied mainly for mild to moderate depression. Can weaken many medicines and interact in dangerous, sometimes life-threatening ways: some antidepressants, birth control pills, cyclosporine, some seizure drugs, digoxin and ivabradine, some HIV and cancer drugs, warfarin, some statins. Serotonin side effects with antidepressants. Sun sensitivity at large doses; diarrhea, dizziness, trouble sleeping. May be unsafe in pregnancy; colic and drowsiness in breastfed infants.
- Huperzine A: Cognitive Vitality. Alzheimer's Drug Discovery Foundation, 2026.From firmoss; works similarly to most Alzheimer's drugs; small, short, high-bias dementia trials at 0.2-0.4 mg a day; no benefit in a study of 84 healthy military personnel; no prevention studies; headache, dizziness, blurred vision, stomach effects; might lower heart rate and worsen some epilepsy; may worsen side effects of donepezil-type drugs; may weaken anticholinergic drugs.
- Signs and Symptoms of Stroke. Centers for Disease Control and Prevention, 2026.Sudden numbness or weakness on one side, confusion, trouble speaking, seeing or walking, severe headache: call 911 right away.
FAQ
St. John's wort interactions: common questions
Which medications should not be taken with St. John's wort?
Ask a pharmacist before combining it with birth control pills, warfarin, some antidepressants, some statins, cyclosporine, digoxin, ivabradine, phenytoin, carbamazepine, or some HIV and cancer drugs (NCCIH, St. John's wort). Some of these interactions can be dangerous. Bring your full medicine list, since others may matter too.
Can I take St. John's wort with sertraline or Lexapro?
Not without your prescriber's approval. NCCIH warns that St. John's wort with some antidepressants can cause serious serotonin side effects (NCCIH, St. John's wort). Keep taking the antidepressant as prescribed and leave MemoPryl out until your doctor or pharmacist has reviewed both.
Does St. John's wort interact with beta blockers like metoprolol?
Beta blockers are not on the NCCIH interaction list, but that is not proof of safety, so ask your pharmacist. MemoPryl itself is a supplement with a similar-sounding name, not metoprolol, so keep the two clearly apart on your medicine list.
Does St. John's wort affect thyroid medication?
Thyroid medicine is not on the NCCIH list for St. John's wort. MemoPryl also contains bacopa, though, and bacopa needs care with thyroid medicine (ADDF, Bacopa). Anyone on thyroid treatment should ask a pharmacist before starting MemoPryl.
Is a small amount of St. John's wort in a blend still a concern?
It can be, and with MemoPryl nobody can measure it, because no amounts are published. Treat the herb as present at an unknown dose and follow the same rule as for a full St. John's wort product: check your medicines with a pharmacist first.
How long does St. John's wort affect other drugs after you stop?
Our cited sources do not give a time. Before starting a new prescription after MemoPryl, ask your pharmacist, and tell every prescriber you took a product with St. John's wort, even if you have stopped.
Who wrote this
Written and reviewed by
Plain-language pages built from the label, the sales page and linked public health sources.
Last updated . Read our editorial standards and how we check reviews. This website is run by a U.S. stocking partner that sells MemoPryl, not by the maker (the pack shots say "By NutraVibe"). We earn money when you buy through our order links.
Keep reading
More about MemoPryl
St. John's wort
St. John's wort weakens many common medicines. The full interaction table, plus pregnancy and sun cautions.
Read moreSide effects
Every reported side effect and drug interaction for MemoPryl's eight named ingredients, with when to stop and when to call 911.
Read moreHuperzine A
Huperzine A acts like a prescription dementia drug. Who should ask first, and which bottle lists it.
Read moreU.S. stocking partner for MemoPryl
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