The short answer
Increased low-pressure risk from Crataegus monogyna with metolazone is not established. Check the species and preparation and discuss symptoms or low readings with your clinician.
What this answer covers
Oral Crataegus monogyna products with metolazone; unidentified hawthorn and C.laevigata evidence are adjacent only.
- Supplement or preparation
- Crataegus monogyna
- Medication ingredient
- metolazone
The short trial was not clearly positive
A short dose-ranging hawthorn leaf-and-flower study found no significant blood-pressure response. It excluded antihypertensive users, and the inspected product description did not specify the species. It therefore cannot establish an interaction in someone taking metolazone.
A second study used another species
A16-week trial of Crataegus laevigata found a small diastolic reduction without a significant systolic difference. Some participants used blood-pressure medicines, but this was not an exact C.monogyna-metolazone comparison. Species and background treatment prevent direct transfer.
Bring the full hawthorn label
Ask the pharmacist to check species, plant part, extract strength and other ingredients. Metolazone’s pressure and fluid effects make symptoms worth reviewing, but they do not establish a routine herb-related dose change or protective spacing interval.
Report symptoms and changes
Report persistent dizziness, cramps, weakness, palpitations or a major change in swelling or urine output. Illness, dehydration and other medicines can contribute. Severe weakness, fainting or a new irregular heartbeat need prompt assessment. Do not treat symptoms by adding salts or increasing the diuretic yourself.
Evidence and practical considerations
Side effects & toxicity
The inspected hawthorn studies do not establish excess hypotension for exact C.monogyna and metolazone co-use.
- Exact scope
- Oral Crataegus monogyna products with metolazone; unidentified hawthorn and C.laevigata evidence are adjacent only. with Exact metolazone RxCUI6916 IN, confirmed by current RxNorm. Exact metolazone oral tablets in conventional2.5/5/10mg formulation; rapidly absorbed formulations are not assumed interchangeable.
- Medication form and route
- Oral
What remains uncertain
- Different or unspecified species, short exposure and no exact co-use subgroup; no clinical hypotension event rate.
Factors that may matter: Exact preparation and dose; Kidney function; Baseline electrolyte status; Other medicines.
Read the supporting source summaries
Source 1: Current prescribing information
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients prescribed oral metolazone tablets.
Recommends electrolyte monitoring and correction if indicated; potassium loss is dose-related. Hyponatremia can be severe. Infrequent hypercalcemia especially with high vitaminD doses or high bone turnover.
How this applies: Exact medication label. Exact metolazone RxCUI6916 IN, confirmed by current RxNorm. Exact metolazone oral tablets in conventional2.5/5/10mg formulation; rapidly absorbed formulations are not assumed interchangeable.
No universal potassium/salt supplementation or fixed vitaminD gap. Other botanicals and diuretics are not automatic exact-pair evidence.
Source 2: Original clinical research
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 21 adults with prehypertension/mild hypertension; antihypertensive users excluded.
No significant dose-response in blood pressure or flow-mediated dilation.
How this applies: Applicability is limited to the stated exact medication, preparation and endpoint; other-drug evidence is indirect.
Very short; no metolazone. Species unspecified in inspected product description, not authenticated C.monogyna.
Source 3: Original clinical research
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 79 adults with type2diabetes;71% used hypotensive medicines.
Small average diastolic reduction, without significant systolic difference.
How this applies: Applicability is limited to the stated exact medication, preparation and endpoint; other-drug evidence is indirect.
Abstract-only, different species and no metolazone-specific group; not proof of C.monogyna-induced hypotension.
Source 4: Medication terminology
rxnav.nlm.nih.gov · Source check Sep 10, 2026
Population: Terminology.
metolazone is IN.
How this applies: Exact ingredient.
Not clinical evidence.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Sources checked and article drafted. | |
| Research summary published |
Article revision: 8cd3fc2b23642fb0
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.