What it's used for
Methenamine mandelate is used to suppress or eliminate bacteria in the urine associated with chronic urinary tract infections such as pyelonephritis and cystitis. It is particularly suitable for long-term therapy.
Source: U.S. FDA-approved prescribing information (openFDA).
Typical dosing
The average adult dose is 4 grams a day taken as one 1000 mg tablet or two 500 mg tablets after each meal and at bedtime. Children aged 6 to 12 years should receive half the adult dose, which is one 500 mg tablet 4 times a day.
Dosing shown here is the general FDA-labeled range. Your prescribing clinician determines the exact dose, form, and schedule for you — this is not a substitute for medical advice.
Boxed warning / key safety info
Methenamine mandelate should be avoided in patients with gout or a predisposition to uric acid stones because it may cause crystals in the urine.
Common side effects
Gastrointestinal disturbances such as nausea and stomach upset, generalized skin rash, and painful or difficult urination may occur occasionally.
Covered strengths on the Tab $0 list
Covered at $0 with an active Tab membership when filled at a participating pharmacy nationwide or through mail order. A licensed clinician must prescribe the medication.
Related medications
Other everything else medications covered at $0 with an active Tab membership.
Methenamine Mandelate cost without insurance
Cash prices for Methenamine Mandelate without insurance vary widely by pharmacy, strength and quantity — the same prescription can cost very different amounts at two pharmacies in the same town. That is the problem a membership solves.
Methenamine Mandelate is on Tab's covered $0 generic list. With an active Tab membership, every covered strength is $0 — not a percentage off, not a coupon that changes month to month — at participating pharmacies nationwide or through mail order. You do not need insurance, and Tab works whether or not you have a health plan.
Tab is a membership, not insurance. Covered medications require a prescription from a licensed clinician.
Methenamine Mandelate dosage and administration
The average adult dose is 4 g a day given as one 1000 mg tablet or two 500 mg tablets after each meal and at bedtime. Children 6 to 12 years of age should receive half the adult dose; one 500 mg tablet, 4 times a day.
Excerpt from the FDA-approved prescribing information (openFDA), retrieved 2026-09-15. Your prescribing clinician decides the exact dose, form and schedule for you — this is not medical advice.
Methenamine Mandelate side effects
Gastrointestinal disturbances (nausea, stomach upset), generalized skin rash, dysuria, painful or difficult urination may occur occasionally with the use of methenamine preparations. Microscopic and rarely, gross hematuria have been described.
Excerpt from the FDA-approved prescribing information (openFDA), retrieved 2026-09-15. This is not a complete list. Report side effects to your clinician, and seek care for anything severe or unexpected.
Methenamine Mandelate drug interactions
Formaldehyde and sulfamethizole form an insoluble precipitate in acid urine; therefore, methenamine mandelate should not be administered concurrently with sulfamethizole or other sulfonamides. Concurrent use of salicylates may lead to increased serum salicylate levels since excretion of salicylates is reduced in acidified urine.
Excerpt from the FDA-approved prescribing information (openFDA), retrieved 2026-09-15. Tell your clinician and pharmacist about every medication, supplement and over-the-counter product you take.
Who should not take methenamine mandelate
Methenamine mandelate tablets are contraindicated in patients with renal insufficiency, severe hepatic disease, severe dehydration, and in patients who have exhibited hypersensitivity to any components of this product.
Excerpt from the FDA-approved prescribing information (openFDA), retrieved 2026-09-15. Whether this medication is appropriate for you is a clinical decision made by your prescribing clinician.
Common questions
Is methenamine Mandelate covered at $0 with Tab?
Yes. Methenamine Mandelate is on Tab's covered $0 generic list — every covered strength is $0 with an active membership, at participating pharmacies nationwide or by mail order.
Do I need insurance to get methenamine Mandelate through Tab?
No. Tab is a membership, not insurance. Covered medications are $0 with an active membership whether or not you have a health plan.
How do I get a methenamine Mandelate prescription with Tab?
Book a video visit with a licensed Tab clinician (unlimited visits are included with membership). If it's clinically appropriate, they send the prescription to your chosen participating pharmacy or by mail order.
How much does methenamine mandelate cost without insurance?
Without insurance, retail cash prices for methenamine mandelate vary by pharmacy, strength and quantity. Methenamine Mandelate is on Tab's covered $0 generic list, so every covered strength is $0 with an active Tab membership at participating pharmacies nationwide or by mail order.
What is the cheapest way to get methenamine mandelate?
For medications on Tab's covered list, a Tab membership is the cheapest route: covered strengths of methenamine mandelate are $0 with an active membership, and unlimited video visits with a licensed clinician are included, so the visit that produces the prescription is covered too.
What is the usual dose of methenamine mandelate?
The average adult dose is 4 g a day given as one 1000 mg tablet or two 500 mg tablets after each meal and at bedtime. Children 6 to 12 years of age should receive half the adult dose; one 500 mg tablet, 4 times a day. (FDA-approved label, retrieved 2026-09-15. Your clinician sets your dose.)
What are the side effects of methenamine mandelate?
Gastrointestinal disturbances (nausea, stomach upset), generalized skin rash, dysuria, painful or difficult urination may occur occasionally with the use of methenamine preparations. Microscopic and rarely, gross hematuria have been described. (FDA-approved label, retrieved 2026-09-15.)
What interacts with methenamine mandelate?
Formaldehyde and sulfamethizole form an insoluble precipitate in acid urine; therefore, methenamine mandelate should not be administered concurrently with sulfamethizole or other sulfonamides. Concurrent use of salicylates may lead to increased serum salicylate levels since excretion of salicylates is reduced in acidified urine. (FDA-approved label, retrieved 2026-09-15. Tell your clinician about every medication and supplement you take.)
Methenamine Mandelate is $0 on the covered list
Members pay $0 for covered generics at participating pharmacies nationwide or by mail order — plus unlimited virtual primary care, urgent care and dermatology visits. No insurance needed.
Solo $49/mo · Family $119/mo for up to 4 people · Family+ $149/mo for up to 8
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