The short answer
It is uncertain whether Crataegus monogyna increases low-blood-pressure risk with terazosin. Hawthorn studies do not establish this exact combination, so review the product and any dizziness with your clinician.
What this answer covers
Oral terazosin and Crataegus monogyna. Human hawthorn studies used an incompletely authenticated leaf-and-flower extract or C.laevigata, a different species.
- Supplement or preparation
- Crataegus monogyna
- Medication ingredient
- terazosin
The human findings are mixed
A short study in 21 adults found no dose-response in blood pressure with a standardized hawthorn extract. A longer study in people with diabetes found a small diastolic reduction but no significant systolic change and no identified herb-drug interaction. The latter used C.laevigata, not the C.monogyna listed here.
Match the botanical carefully
The species, leaf-and-flower versus berry preparation, extraction method and daily amount matter. The short study did not authenticate its product as C.monogyna. Neither study establishes a safe dose, a harmful dose or a dose reduction for someone taking terazosin.
Discuss use before changing treatment
Terazosin can cause postural hypotension on its own. Share your supplement label, blood-pressure readings and recent medication changes. Do not substitute hawthorn for prescribed treatment or assume separating the doses makes an unstudied combination safe.
Respond to symptoms
Terazosin can cause dizziness, lightheadedness or fainting, particularly when treatment begins or the dose changes. Report troublesome symptoms to the prescriber; sit or lie down if you feel faint and avoid hazardous activity while affected. A blood-pressure reading and the timing of symptoms can help distinguish a medication effect from an unproven supplement interaction. The label also cautions about restarting after a treatment interruption; ask the prescriber how to restart.
Evidence and practical considerations
Side effects & toxicity
Mixed and species-limited hawthorn BP studies do not establish harmful C.monogyna co-use with terazosin.
- Exact scope
- Oral terazosin and Crataegus monogyna. Human hawthorn studies used an incompletely authenticated leaf-and-flower extract or C.laevigata, a different species. with Current RxNorm confirms terazosin RxCUI 37798 IN. Oral hydrochloride capsules provide equivalent terazosin 1, 2, 5 or 10 mg.
- Medication form and route
- Oral
What remains uncertain
- No exact pair trial; species and plant-part boundaries, short duration and null findings retained.
Factors that may matter: Exact preparation and dose; Blood pressure and symptoms; Treatment initiation or dose change; Other medicines.
Read the supporting source summaries
Source 1: Current prescribing information
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients prescribed terazosin hydrochloride capsules.
First-dose and postural hypotension/syncope; caution after dose escalation or restarting interrupted therapy.
How this applies: Exact ingredient through the stated labeled salt and oral formulation. Current RxNorm confirms terazosin RxCUI 37798 IN. Oral hydrochloride capsules provide equivalent terazosin 1, 2, 5 or 10 mg.
No automatic transfer of another alpha blocker’s doses or timing; exact label used.
Source 2: Original clinical research
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 21 adults with prehypertension or mild hypertension; antihypertensive users excluded.
No significant dose-response in blood pressure or flow-mediated dilation.
How this applies: Exact preparation and endpoint boundaries retained; this is not a measured terazosin combination unless explicitly stated.
Short study; species not authenticated as C.monogyna in the inspected product description. No terazosin co-use.
Source 3: Original clinical research
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 79 adults with type 2 diabetes; 71% used hypotensive medicines.
Small mean diastolic reduction, no significant systolic difference and no herb-drug interaction found.
How this applies: Exact preparation and endpoint boundaries retained; this is not a measured terazosin combination unless explicitly stated.
Abstract-only; different species, no terazosin subgroup. Neither a harmful C.monogyna interaction nor universal safety follows.
Source 4: Medication terminology
rxnav.nlm.nih.gov · Source check Sep 10, 2026
Population: Terminology.
terazosin 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: 9b977fafc308b7fc
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.