Olive Leaf (Olea europaea): Benefits, Dosage, Safety & Evidence

What is a herb–drug interaction?

A herb–drug interaction happens when a plant or supplement changes how a medication works in your body — making it stronger, weaker, or more likely to cause harm. Herbs contain active compounds that can speed up or slow down the enzymes and transporters your body uses to process drugs.

Why it matters

St. John's Wort can make birth control, antidepressants, and blood thinners less effective.

Garlic can increase bleeding risk with warfarin and other blood thinners (also ginkgo, ginger, and turmeric).

Kava can amplify sedation when taken with anxiety or sleep medications (also valerian).

The risk is highest for older adults, anyone taking several medications, and people with chronic conditions.

Always tell your doctor and pharmacist about every herb and supplement you take — and check below before combining.

Known Drug Interactions (2)

2 Moderate

Drug	Severity	Description
Diabetes medications	Moderate	Olive leaf extract may enhance blood sugar-lowering effects of diabetes medications.
Antihypertensives (general)	Moderate	Olive leaf extract has blood pressure-lowering properties that may be additive with antihypertensive medications.

This list reflects a curated subset of documented interactions and is not exhaustive. The absence of a drug here is not proof that it is safe to combine. Always confirm with a pharmacist or healthcare provider.

Frequently asked questions

How does olive leaf extract lower blood pressure?

Olive leaf extract works primarily through its active compound oleuropein, which functions as a vasodilator to relax arterial walls and improve blood flow. Research suggests it may also inhibit angiotensin-converting enzyme (ACE), similar to some pharmaceutical blood pressure medications. Additionally, its antioxidant properties help reduce oxidative stress on the cardiovascular system. Evidence level: C.

Can I take olive leaf extract with blood pressure medication?

Caution is advised when combining olive leaf extract with prescription antihypertensive medications. Because olive leaf has natural blood pressure-lowering properties, taking it alongside medication may cause hypotension (blood pressure that is too low), leading to dizziness or fainting. If you are on blood pressure medication, consult your healthcare provider for monitoring before adding olive leaf to your regimen. Evidence level: C.

Is olive leaf extract safe during pregnancy?

Olive leaf extract is considered unsafe during pregnancy and breastfeeding. There is insufficient safety data for expecting mothers, and traditional sources suggest it may stimulate the uterus or affect fetal development. Due to these potential risks and the lack of clinical evidence confirming safety, pregnant women should avoid olive leaf supplements unless specifically prescribed by a qualified healthcare professional.

What is the recommended dosage for olive leaf extract?

The standard adult dosage for olive leaf extract is 500 to 1000 mg daily. To ensure therapeutic effects, look for a standardized extract containing 15-20% oleuropein, the primary active compound. Dosage may vary based on the specific health goal, such as immune support versus blood pressure management. Always follow manufacturer instructions or consult a medical herbalist. Evidence level: C.

What are the side effects of taking olive leaf extract?

Common side effects include gastrointestinal upset, acid reflux, headache, and dizziness. Some individuals may experience a Herxheimer reaction (die-off reaction), which causes temporary flu-like symptoms as the body eliminates pathogens. To minimize stomach upset, take the supplement with food. If dizziness occurs, it may indicate blood pressure is dropping too low. Evidence level: Traditional.

PubMed-compiled information sheet

This sheet was compiled from PubMed (NIH) abstracts using AI assistance. Every factual claim is cited to a real PubMed article (see the source list). It has not yet been human-reviewed — confirm with a healthcare provider before use.

Compiled from 30 PubMed articles · model: gemma4:31b

Summary

Olive leaf (Olea europaea) is used in traditional medicine for its potential hypoglycemic, hypolipidemic, and antioxidant properties [PMID:31901903, PMID:25726243].

Background

Olea europaea is an evergreen tree widely cultivated in the Mediterranean basin [PMID:39124213]. Its leaves are a concentrated reservoir of bioactive molecules, often containing higher phenolic levels than the fruit or oil [PMID:42280398].

Traditional uses

Olive leaves have been widely used in traditional herbal medicine, particularly in Mediterranean countries, to prevent and treat various diseases [PMID:31901903] and as anti-inflammatory agents [PMID:28731213].

Active compounds

The primary phenolic compound is oleuropein [PMID:31901903, PMID:25726243]. Other active compounds include luteolin and its glycosides [PMID:42287884], as well as hydroxytyrosol and oleuropeoside [PMID:34676481, PMID:28731213].

Mechanism of action

Olive leaf extract (OLE) exhibits antioxidant and anti-inflammatory activities [PMID:37686133]. It can suppress pro-inflammatory mediators such as TNF-α, IL-6, and IL-1β [PMID:33260769], reduce oxidative stress by augmenting antioxidant enzyme activities [PMID:28463797], and inhibit apoptotic signaling pathways in fibroblasts [PMID:36014384].

Clinical evidence

Evidence BStage-1 Hypertension

Olive leaf extract (500 mg twice daily) was evaluated for its anti-hypertensive and hypolipidemic effects in comparison with Captopril [PMID:21036583].

Evidence BPostmenopausal Symptoms

Supplementation with 250 mg/day of OLE for 12 weeks significantly improved overall MENQoL scores and bone mineral density in the right arm compared to placebo [PMID:39599665].

Evidence BType 2 Diabetes Mellitus

A pilot randomized controlled trial found no statistically significant time-group interaction for the change in HbA1c after 24 weeks of OLE capsules [PMID:39818111].

Safety & adverse effects

Toxicity studies suggest that olive leaf is generally safe, even at high doses [PMID:31901903].

Evidence summary

Evidence ranges from in vitro and animal models (showing strong anti-inflammatory, antimicrobial, and neuroprotective potential) to small-scale human RCTs. Human evidence is mixed, showing efficacy for postmenopausal symptoms and hypertension, but lack of significant effect on HbA1c in a pilot T2DM study.

PubMed sources

1.PMID: 31901903 (2020) — Olive Leaf (Olea europaea L. folium): Potential Effects on Glycemia and Lipidemia. · Annals of nutrition & metabolism
2.PMID: 35614890 (2022) — Olea europaea L. (olive) leaf extract ameliorates learning and memory deficits in streptozotocin-induced diabetic rats. · Avicenna journal of phytomedicine
3.PMID: 25726243 (2014) — Polyphenols benefits of olive leaf (Olea europaea L) to human health. · Nutricion hospitalaria
4.PMID: 39818111 (2025) — Efficacy and safety of olive leaf extract (Olea europaea L.) for glycaemic control in adults with type 2 diabetes mellitus (ESOLED): A pilot randomised controlled trial. · Complementary therapies in clinical practice
5.PMID: 36181589 (2023) — Olive leaf (Olea europaea L. folium) extract influences liver microsomal detoxifying enzymes in rats orally exposed to 2-amino-l-methyI-6-phenyI-imidazo pyridine (PhIP).

Olive Leaf

Sources & Citations

Calculate a safe dose of Olive Leaf

Garlic

Black Garlic

Hawthorn Korean

⚠️ Not Recommended During Pregnancy or Nursing

2 Known Drug Interactions — Some May Be Serious

Contraindications

Possible Side Effects

What is a herb–drug interaction?

Known Drug Interactions (2)

Frequently asked questions

Summary

Background

Traditional uses

Active compounds

Mechanism of action

Clinical evidence

Safety & adverse effects

Evidence summary

PubMed sources

Government sources

Olive Leaf

Sources & Citations

Calculate a safe dose of Olive Leaf

Related Herbs

Garlic

Black Garlic

Hawthorn Korean

⚠️ Not Recommended During Pregnancy or Nursing

2 Known Drug Interactions — Some May Be Serious

Contraindications

Possible Side Effects

What is a herb–drug interaction?

Known Drug Interactions (2)

Frequently asked questions

Summary

Background

Traditional uses

Active compounds

Mechanism of action

Clinical evidence

Safety & adverse effects

Evidence summary

PubMed sources

Government sources