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Methenamine / sodium salicylate Side Effects

Applies to methenamine / sodium salicylate: oral tablet.

This medicine can increase your risk of fatal heart attack or stroke. Do not use this medicine just before or after heart bypass surgery (coronary artery bypass graft, or CABG). This medicine may also cause stomach or intestinal bleeding, which can be fatal.

Get emergency medical help if you have signs of an allergic reaction: sneezing, runny or stuffy nose; wheezing or trouble breathing; hives; swelling of your face, lips, tongue, or throat.

Stop using this medicine and call your doctor at once if you have:

  • ringing in your ears;

  • a light-headed feeling, like you might pass out;

  • new or worsening stomach pain; or

  • bloody or tarry stools, coughing up blood or vomit that looks like coffee grounds.

Less serious side effects may be more likely, and you may have none at all.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.