Methenamine Sodium Salicylate Benzoic Acid

Methenamine/Sodium salicylate/Benzoic acid is an over-the-counter medication used for the prevention of urinary tract infections.

• Methenamine/Sodium salicylate/Benzoic acid is available under the following different brand names: Cystex

Adult and pediatric dosage

Tablet

• 162mg/162.5mg/32mg

Urinary Tract Infection Prophylaxis

Adult dosage

• 2 tablets orally every 12hours

Pediatric dosage

• Children below 16 years: Safety/efficacy not established
• Children above 16 years: 2 tablets orally every 6hours

Dosage Considerations – Should be Given as Follows: 

• See “Dosages”

Common side effects of Methenamine Sodium Aalicylate Benzoic Acid include:

• dysuria,
• nausea,
• rash, and 
• gastric upset.

Serious side effects of Methenamine Sodium Aalicylate Benzoic Acid include:

• hearing loss,
• angioedema
• bronchospasm,
• CNS alteration,
• dermatologic problems,
• GI pain/ulceration/bleeding, and
• hepatotoxicity

Rare side effects of Methenamine/Sodium salicylate/Benzoic acid include:

• none 

This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

• Methenamine Sodium Aalicylate Benzoic Acid has no noted severe interactions with any other drugs.
• Methenamine Sodium Aalicylate Benzoic Acid has no noted serious interactions with any other drugs.
• Methenamine Sodium Aalicylate Benzoic Acid has no noted moderate interactions with any other drugs.
• Methenamine Sodium Aalicylate Benzoic Acid has no noted minor interactions with any other drugs. 

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns.

Contraindications

• Methenamine
• Hypersensitivity to methenamine or tartrazine (FD&C Yellow No. 5)
• Renal or severe hepatic insufficiency
• Concurrent sulfonamides or acetazolamide may form insoluble precipitate in urine
• Sodium Salicylate
• Hypersensitivity to aspirin or NSAIDs
• Bleeding gastrointestinal ulcers
• Asthma, Nasal polyps associated with asthma
• Hemolytic anemia from PK & G6PD deficiency
• Hemophilia
• Hemorrhagic diathesis
• Hemorrhoids, Lactating women, Sarcoidosis, Thrombocytopenia, Ulcerative colitis

Effects of drug abuse

• None

Short-Term Effects

• See “What Are Side Effects Associated with Using Methenamine/Sodium salicylate/Benzoic acid?”

Long-Term Effects

• See “What Are Side Effects Associated with Using Methenamine/Sodium salicylate/Benzoic acid?”

Cautions

• Methenamine
• Large doses may cause bladder irritation, urinary frequency, albuminuria, and hematuria
• Maintain acidic pH of urine, especially when treating urea-splitting organisms (eg, Proteus, Pseudomonas)
• Monitor LFTs, especially with a history of liver impairment
• Safe use is not established during pregnancy, especially 1st and 2nd trimester
• May precipitate uric acid stones in patients with gout
• Sodium Salicylate
• Anemia
• GI malabsorption
• History of peptic ulcers
• Gout
• Hepatic disease
• Hypochlorhydria, Hypoprothrombinemia, Renal impairment, Renal calculi, Thyrotoxicosis, Vitamin K deficiency

Pregnancy and Lactation

• Use with caution if benefits outweigh risks during pregnancy
• Lactation
  • Methenamine is excreted in human milk; caution advised, the risk to infant cannot be ruled out