Methenamine and Sodium Acid Phosphate

• If you have an allergy to methenamine and sodium acid phosphate or any other part of methenamine and sodium acid phosphate.
• If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Tell your doctor about the allergy and what signs you had, like rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other signs.
• If you have any of these health problems: High phosphate levels in your blood, kidney disease, or if you have a lot of fluid loss (dehydrated).
• If you are taking sulfamethizole.
• If you are taking a sulfa (sulfonamide) drug. Ask your doctor if you are not sure if any of your drugs are a sulfa drug.

This is not a list of all drugs or health problems that interact with this medicine.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take methenamine and sodium acid phosphate with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

• Tell all of your health care providers that you take this medicine. This includes your doctors, nurses, pharmacists, and dentists.
• Talk with your doctor before you take aspirin, antacids, or drugs that raise the pH of the urine while on methenamine and sodium acid phosphate.
• You may need to check the acid content (pH) of your urine using a dipstick test.
• Talk with your doctor before you eat citrus fruits, dairy products, and some veggies while taking this medicine.
• If you are on a low-salt or salt-free diet, talk with your doctor.
• This medicine may affect certain lab tests. Tell all of your health care providers and lab workers that you take methenamine and sodium acid phosphate.
• Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using this medicine while you are pregnant.
• Tell your doctor if you are breast-feeding. You will need to talk about any risks to your baby.

• Store at room temperature.
• Store in a dry place. Do not store in a bathroom.
• Protect from light.
• Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
• Check with your pharmacist about how to throw out unused drugs.

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
• Very upset stomach or throwing up.
• Belly pain.
• Bone or joint pain.
• Blood in the urine.
• Bladder pain or pain when passing urine or change in how much urine is passed.
• Mood changes.
• Feeling confused.
• Muscle cramps.
• Numbness or tingling around the mouth.
• Numbness or tingling in the hands or feet.
• Seizures.
• More thirst.
• Feeling very tired or weak.
• A big weight gain.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Upset stomach.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-FDA-1088. You may also report side effects at http://www.fda.gov/medwatch.

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