Methenamine Side Effects

Brand Names: Hiprex

Please note - some side effects for Methenamine may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

Side Effects of Methenamine - for the Consumer

Methenamine

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Methenamine:

Nausea; upset stomach.

Seek medical attention right away if any of these SEVERE side effects occur when using Methenamine:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blood in the urine.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.

Methenamine/Sodium Biphosphate

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Methenamine/Sodium Biphosphate:

Nausea; upset stomach.

Seek medical attention right away if any of these SEVERE side effects occur when using Methenamine/Sodium Biphosphate:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blood in the urine; bone or joint pain; increased, decreased, or painful urination; mental or mood changes; muscle cramps; numbness or tingling of the lips, hands, or feet; seizures; stomach pain; unusual thirst; unusual weakness; unusual weight gain; vomiting.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.

Methenamine/Sodium Phosphate

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Methenamine/Sodium Phosphate:

Nausea; upset stomach.

Seek medical attention right away if any of these SEVERE side effects occur when using Methenamine/Sodium Phosphate:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blood in the urine; bone or joint pain; increased, decreased, or painful urination; mental or mood changes; muscle cramps; numbness or tingling of the lips, hands, or feet; seizures; stomach pain; unusual thirst; unusual weakness; unusual weight gain; vomiting.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.

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Methenamine Side Effects - for the Professional

Methenamine

Minor adverse reactions have been reported in less than 3.5% of patients treated. These reactions have included nausea, upset stomach, dysuria, and rash.

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Side Effects by Body System - for Healthcare Professionals

General

Methenamine is generally well tolerated. Minor side effects have been reported in less than 3.5% of patients.

Dermatologic

Dermatologic side effects have included rash and pruritus.

Gastrointestinal

Gastrointestinal side effects have included nausea, vomiting, diarrhea, anorexia, and abdominal cramping.

Genitourinary

Genitourinary side effects have included dysuria, hematuria, and urinary frequency. High doses have been associated with albuminuria, gross hematuria, bladder wall irritation, and painful/frequent micturition.

Hepatic

Methenamine is contraindicated in patients with severe liver disease due to the risk of systemic acidosis.

Hepatic side effects have rarely included transient elevations of AST (SGOT) and ALT (SGPT).

Hypersensitivity

Hypersensitivity reactions have included rashes in 1% to 4% of patients.

Respiratory

Respiratory system side effects may occur in patients with a poor gag reflex or a swallow disorder. Methenamine oral suspension has a vegetable base, and should be used with caution in elderly patients and in those with swallow disorders to prevent lipid pneumonia. Long-term therapy with methenamine suspension has been associated with lipoid pneumonitis in elderly patients.

Ocular

Ocular side effects have included rare cases of anterior uveitis.

Renal

Renal side effects have been more likely and more severe in patients with mild to moderate renal insufficiency. Methenamine is contraindicated in patients with severe renal insufficiency.

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