Supplement analysis backed by scientific evidence · PT · ES · DE · FR

← All supplements
Limited evidenceGut health

Oregano Oil

Oregano oil is a genuinely potent antimicrobial in a petri dish and almost untested in humans — one 14-person open-label parasite study is the most-cited clinical evidence there is. Treat the SIBO, candida and "natural antibiotic" claims as unproven.

View on iHerb Ships to 180+ countries · welcome discount for new customers

What the science says

  • Intestinal parasites and gut microbes Limited evidence

    The single most-cited human study gave 600 mg/day of emulsified oregano oil for 6 weeks to 14 adults with enteric parasites; Blastocystis hominis cleared in 8 of 11 cases and GI symptoms improved in 7 of 11. It was uncontrolled, unblinded and tiny — hypothesis-generating at best, and it has never been replicated in a randomized trial.

  • Antibacterial and antifungal activity Limited evidence

    Carvacrol and thymol disrupt bacterial membranes and inhibit Staphylococcus aureus, E. coli, Candida albicans and many others at low concentrations in vitro, which is why oregano oil dominates laboratory antimicrobial screens. Reaching those concentrations in the human gut or bloodstream after oral dosing has not been demonstrated, and no clinical trial shows it treats an infection.

  • SIBO and candida protocols Limited evidence

    Oregano oil is a staple of herbal SIBO protocols, but the trial usually cited for these regimens tested multi-herb combinations, not oregano oil alone, so no effect can be attributed to it. There is no controlled evidence at all for oral oregano oil in candida overgrowth.

Dosage & safety

Studied doseThe parasite study used 600 mg/day of emulsified oregano oil for 6 weeks. Commercial capsules typically supply 100-600 mg/day of oil standardized to 50-85% carvacrol, or a few drops of diluted oil, usually for 2-4 weeks. No dose has been validated in a randomized trial, and undiluted essential oil should never be swallowed.
SafetyUndiluted oregano essential oil is caustic and can burn the mouth, oesophagus and skin — always dilute or use enteric capsules. Common effects are heartburn, nausea and burping. It may lower blood glucose and has antiplatelet activity in vitro, so use caution with antidiabetic drugs, anticoagulants and before surgery. It can reduce iron absorption when taken with meals. People allergic to Lamiaceae plants (mint, basil, sage, lavender) may react. Avoid in pregnancy — traditional use as an emmenagogue and animal data raise concern — and do not give to infants or young children. It is antibacterial without selectivity, so prolonged use as a routine "gut cleanse" is not benign.

How to take it

TimingTiming does not matter; keep courses to 2-4 weeks.
With food?Take it with food, and only as a diluted or enteric-coated capsule - undiluted essential oil burns the mouth and oesophagus.
Worth knowingIt is a non-selective antibacterial, so running it continuously as a gut cleanse hits your commensal bacteria along with everything else.

Interactions

With medications

  • insulin and other antidiabetic drugs

    Oregano oil may lower blood glucose additively. monitor your glucose during the course

  • warfarin, DOACs and antiplatelet drugs

    Carvacrol has antiplatelet activity in vitro. tell your prescriber and stop it before surgery

With other supplements

  • iron supplements

    Oregano polyphenols bind non-haem iron and reduce its absorption. separate by at least 2 hours

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does oregano oil work as a natural antibiotic?

Oregano oil is a potent antimicrobial in the lab, but no clinical trial shows it treats an infection in humans and reaching effective concentrations in the body has not been demonstrated. The evidence is limited.

Does oregano oil work for SIBO or candida?

There is no controlled evidence for oregano oil alone in SIBO or candida: the SIBO trial usually cited tested multi-herb combinations. Treat these claims as unproven.

Can oregano oil get rid of parasites?

The main human study gave 600 mg/day of emulsified oregano oil for 6 weeks to 14 adults and reported Blastocystis cleared in 8 of 11 cases. It was uncontrolled, unblinded and never replicated, so this evidence is limited.

Is oregano oil safe to take?

Undiluted oregano oil is caustic and can burn the mouth and oesophagus, so only use diluted or enteric-coated capsules, and keep courses to 2-4 weeks. Avoid it in pregnancy and in young children, and take care if you use diabetes medication or anticoagulants.

Scientific references

Where to buy

NOW Foods, Oregano Oil, 90 Softgels

View on iHerb

Ships to 180+ countries · welcome discount for new customers

Referral link — this site may earn a commission on purchases.

Related in Gut health