What the FDA labels say about taking them together
Captopril/hydrochlorothiazide and methenamine
Captopril/hydrochlorothiazide's FDA label of February 21, 2023 names methenamine in its drug interactions section; the methenamine labels PlainMeds reads (2) do not name captopril/hydrochlorothiazide. The captopril/hydrochlorothiazide label: “Methenamine: possible decreased effectiveness due to alkalinization of the urine.”
Check it at the source: the captopril/hydrochlorothiazide FDA label on DailyMed (effective February 21, 2023, Rising Pharma Holdings, Inc.); the methenamine FDA label on DailyMed (effective August 7, 2026, ANI Pharmaceuticals, Inc.).
What does the captopril/hydrochlorothiazide label say about methenamine?
Captopril/hydrochlorothiazide label, drug interactionsMethenamine: possible decreased effectiveness due to alkalinization of the urine.
Source: FDA drug label (CAPTOPRIL AND HYDROCHLOROTHIAZIDE), Rising Pharma Holdings, Inc., effective February 21, 2023 (SPL set 0ea90fd4-0da6-4ad2-ab83-6cfbe0ae515e), via openFDA; the full label on DailyMed
What does the methenamine label say about captopril/hydrochlorothiazide?
Methenamine's label (effective August 7, 2026) and its 1 other brand-application label do not name captopril/hydrochlorothiazide in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Methenamine Hippurate), ANI Pharmaceuticals, Inc., effective August 7, 2026 (SPL set a3eeacd4-1983-49ec-a60d-3abaf505ce57), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Captopril/hydrochlorothiazide | Methenamine | |
|---|---|---|
| Labeled for | High blood pressure | Urinary tract infections |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | n/a | $0.313 per tablet 1 g tablet |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once