Do not take this medication with any of the following:
-Cidofovir
-Ketorolac
-Probenecid
This medication may also interact with the following:
-Alcohol
-Certain medications for diabetes
-Certain medications for gout
-Certain medications that prevent and treat blood clots, such as warfarin, enoxaparin, dalteparin, apixaban, dabigatran, and rivaroxaban
-Diuretics
-Other NSAIDs, medications for pain and inflammation, such as ibuprofen or naproxen
-Steroid medications, such as prednisone or cortisone

They need to know if you have any of these conditions:
-Bleeding disorder
-Dehydration
-Diet low in salt
-Frequently drink alcohol
-Gout
-Heart disease
-High blood pressure
-Kidney disease
-Liver disease
-Stomach ulcers, other stomach or intestine problems
-An unusual or allergic reaction to methenamine, sodium salicylate, NSAIDs, other medications, foods, dyes, or preservatives
-Pregnant or trying to get pregnant
-Breast-feeding

Visit your care team for regular checks on your progress. Tell your care team if your symptoms do not start to get better or if they get worse. If you need to use this medication for more than 3 days, talk to your care team.
Check with your care team if you have severe diarrhea, nausea, and vomiting, or if you sweat a lot. The loss of too much body fluid may make it dangerous for you to take this medication.
Do not take other medications that contain aspirin, ibuprofen, or naproxen with this medication. Side effects such as stomach upset, nausea, or ulcers may be more likely to occur. Many non-prescription medications contain aspirin, ibuprofen, or naproxen. Always read labels carefully.
This medication can cause serious ulcers and bleeding in the stomach. It can happen with no warning. Smoking, drinking alcohol, older age, and poor health can also increase risks. Call your care team right away if you have stomach pain or blood in your vomit or stool.
Alcohol may interfere with the effect of this medication. Avoid alcoholic drinks.
This medication may cause serious skin reactions. They can happen weeks to months after starting the medication. Contact your care team right away if you notice fevers or flu-like symptoms with a rash. The rash may be red or purple and then turn into blisters or peeling of the skin. Or, you might notice a red rash with swelling of the face, lips, or lymph nodes in your neck or under your arms.
Talk to your care team if you are pregnant before taking this medication. Taking this medication between weeks 20 and 30 of pregnancy may harm your unborn baby. Your care team will monitor you closely if you need to take it. After 30 weeks of pregnancy, do not take this medication.

Keep out of the reach of children and pets.
Store between 15 and 30 degrees C (59 and 86 degrees F). Protect from light. Get rid of any unused medication after the expiration date.
To get rid of medications that are no longer needed or have expired:
-Take the medication to a medication take-back program. Check with your pharmacy or law enforcement to find a location.
-If you cannot return the medication, check the label or package insert to see if the medication should be thrown out in the garbage or flushed down the toilet. If you are not sure, ask your care team. If it is safe to put it in the trash, take the medication out of the container. Mix the medication with cat litter, dirt, coffee grounds, or other unwanted substance. Seal the mixture in a bag or container. Put it in the trash.