Urex

Methenamine may cause an upset stomach. Take methenamine with food or milk.

In the U.S.

• Hiprex
• Mandelamine
• Urex

In Canada

• Urasal

Available Dosage Forms:

• Tablet
• Suspension
• Tablet, Enteric Coated

Therapeutic Class: Antiseptic

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Although there is no special information comparing use of methenamine in children with use in other age groups, this medicine is not expected to cause different side effects or problems in children than it does in adults.

Geriatric

Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of methenamine in the elderly with use in other age groups.

Pregnancy

Breast Feeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with Medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

• Acetazolamide
• Mafenide
• Silver Sulfadiazine
• Sulfabenzamide
• Sulfacetamide
• Sulfacytine
• Sulfadiazine
• Sulfamerazine
• Sulfamethazine
• Sulfamethoxazole
• Sulfanilamide
• Sulfapyridine
• Sulfasalazine
• Sulfathiazole
• Sulfisoxazole
• Zonisamide

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Dehydration (severe) or
• Kidney disease (severe)—Patients with severe kidney disease who take methenamine may have an increase in side effects that affect the kidneys

• Liver disease (severe)—Patients with severe liver disease who take methenamine may have an increase in symptoms of their liver disease

Applies to methenamine: compounding powder, oral suspension, oral tablet

General

This drug was generally well tolerated. Minor side effects have been reported in less than 3.5% of patients and were reversible when the drug was stopped.[Ref]

Dermatologic

Uncommon (0.1% to 1%): Rash, pruritus
Frequency not reported: Generalized skin rash[Ref]

Gastrointestinal

Uncommon (0.1% to 1%): Gastric irritation
Frequency not reported: Nausea, vomiting, upset stomach, stomatitis, gastrointestinal disturbances, diarrhea, abdominal cramping[Ref]

Genitourinary

High doses have been associated with albuminuria, gross hematuria, bladder irritation, and painful/frequent micturition.[Ref]

Uncommon (0.1% to 1%): Bladder irritation
Frequency not reported: Dysuria, hematuria, urinary frequency, albuminuria[Ref]

Hepatic

Frequency not reported: Elevated AST, elevated ALT[Ref]

Hypersensitivity

Frequency not reported: Hypersensitivity reactions[Ref]

Metabolic

Frequency not reported: Anorexia

Ocular

Frequency not reported: Anterior uveitis[Ref]

Some side effects of Urex may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.