Methenamine, Oral

What are other names for this medicine?

Type of medicine: urinary antiseptic

Generic and brand names: methenamine compounds, oral; methenamine hippurate, oral; methenamine mandelate, oral; Atrosept; Cystex; Dolsed; Hiprex; Mandelamine; Mandelamine Forte; Urex; Urisedamine; Uro-Phosphate; Urogesic Blue; Uroquid Acid #2; Urimax; MHP-A

What is this medicine used for?

This medicine is taken by mouth to treat infections of the urinary tract.

What should my healthcare provider know before I take this medicine?

Before taking this medicine, tell your healthcare provider if you have ever had:

• an allergic reaction to methenamine, formaldehyde, tartrazine or aspirin
• gout
• kidney disease
• liver disease

Females of childbearing age: Tell your healthcare provider if you are pregnant or if you plan to become pregnant while taking this medicine. It is not known whether this medicine will harm an unborn baby. Do not breast-feed while taking this medicine without your healthcare provider's approval.

How do I use it?

This medicine comes in tablet and liquid (suspension) forms. If you have the coated tablets, swallow them whole. Do not break, crush, or chew them. If you have the liquid form, shake the bottle well before using.

You may take this medicine with or without food. Taking it with meals may lessen the chance the drug will upset your stomach.

Check the label on the medicine for directions about your specific dose. Take this medicine in evenly spaced doses for the length of time prescribed. Take each dose with a full glass of water. Do not miss doses. Drink water or cranberry juice between doses.

What if I miss a dose?

If you miss a dose, take it as soon as you remember unless it is almost time for the next scheduled dose. In that case, skip the missed dose and take the next one as directed. Do not take double doses. If you are not sure of what to do if you miss a dose, or if you miss more than one dose, contact your healthcare provider.

What if I overdose?

Symptoms of an acute overdose have not been reported.

What should I watch out for?

You may need regular urine tests to check whether there is enough acid for the medicine to work. Avoid citrus fruits, fruit juices, milk, and dairy products, which can decrease the amount of acid in the urine. Use antacids only if your healthcare provider approves.

Contact your healthcare provider if your condition does not improve in a few days or if it gets worse.

Some forms of this medicine may change the color of your urine, sometimes making it a bright blue. This is not harmful.

What are the possible side effects?

Along with its needed effects, your medicine may cause some unwanted side effects. Some side effects may be very serious. Some side effects may go away as your body adjusts to the medicine. Tell your healthcare provider if you have any side effects that continue or get worse.

Serious (report these to your healthcare provider right away): Trouble breathing, skin rash, hives, painful urination, red or orange colored urine, mouth sores, severe stomach upset.

Other: Nausea, vomiting, headache, loss of appetite.

What products might interact with this medicine?

When you take this medicine with other medicines, it can change the way this or any of the other medicines work. Nonprescription medicines, vitamins, natural remedies, and certain foods may also interact. Using these products together might cause harmful side effects. Talk to your healthcare provider if you are taking:

• acetazolamide (Diamox)
• antacids such as sodium bicarbonate, Maalox, or Mylanta
• citrus fruits and juices, milk, and dairy products
• sulfonamide antibiotics such as sulfamethoxazole (Gantanol), sulfamethizole (Thiosulfil), and sulfamethoxazole and trimethoprim (Septra, Bactrim)
• typhoid vaccine

Keep a list of all your medicines with you. List all the prescription medicines, nonprescription medicines, supplements, natural remedies, and vitamins that you take. Be sure that you tell all healthcare providers who treat you about all the products you are taking.

This advisory includes selected information only and may not include all side effects of this medicine or interactions with other medicines. Ask your healthcare provider or pharmacist for more information or if you have any questions.

Ask your pharmacist for the best way to dispose of outdated medicine or medicine you have not used. Do not throw medicine in the trash.

Keep all medicines out of the reach of children.

Do not share medicines with other people.