What the FDA labels say about taking them together
Fosinopril/hydrochlorothiazide and methenamine
Fosinopril/hydrochlorothiazide's FDA label of April 28, 2024 names methenamine in its drug interactions section; the methenamine labels PlainMeds reads (2) do not name fosinopril/hydrochlorothiazide. The fosinopril/hydrochlorothiazide label: “By alkalinizing the urine, hydrochlorothiazide may decrease the effectiveness of methenamine.”
Check it at the source: the fosinopril/hydrochlorothiazide FDA label on DailyMed (effective April 28, 2024, Aurobindo Pharma Limited); the methenamine FDA label on DailyMed (effective August 7, 2026, ANI Pharmaceuticals, Inc.).
What does the fosinopril/hydrochlorothiazide label say about methenamine?
Fosinopril/hydrochlorothiazide label, drug interactionsBy alkalinizing the urine, hydrochlorothiazide may decrease the effectiveness of methenamine.
Source: FDA drug label (Fosinopril Sodium and Hydrochlorothiazide), Aurobindo Pharma Limited, effective April 28, 2024 (SPL set 35019655-9a30-4305-a262-936ad0e73071), via openFDA; the full label on DailyMed
What does the methenamine label say about fosinopril/hydrochlorothiazide?
Methenamine's label (effective August 7, 2026) and its 1 other brand-application label do not name fosinopril/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
| Fosinopril/hydrochlorothiazide | Methenamine | |
|---|---|---|
| Labeled for | High blood pressure | Urinary tract infections |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.634 per tablet 10-12.5 mg tablet | $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