-antacids
-atropine
-antihistamines for allergy, cough and cold
-certain antibiotics like sulfacetamide and sulfamethoxazole
-certain medicines for bladder problems like oxybutynin, tolterodine
-certain medicines for blood pressure like hydrochlorothiazide
-certain medicines for depression, anxiety or psychotic disturbances
-certain medicines for stomach problems like dicyclomine, hyoscyamine
-certain medicines for travel sickness like scopolamine
-certain medicines for Parkinson''s disease like benztropine, trihexyphenidyl
-ipratropium
-ketoconazole
-MAOIs like Carbex, Eldepryl, Marplan, Nardil, and Parnate
-narcotic medicines for pain

They need to know if you have any of these conditions:
-bladder or prostate problems or trouble passing urine
-dehydration
-glaucoma
-heart disease
-high blood pressure
-high levels of phosphate in the blood
-high levels of sodium in the blood
-kidney disease
-liver disease
-myasthenia gravis
-sodium (salt) restricted diet
-stomach problems
-an unusual or allergic reaction to methenamine, formaldehyde, sodium acid phosphate, methylene blue, hyoscyamine, other medicines, foods, dyes, or preservatives
-pregnant or trying to get pregnant
-breast-feeding

Tell your doctor or healthcare professional if your symptoms do not start to get better or if they get worse.

You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how this medicine affects you. Do not stand or sit up quickly, especially if you are an older patient. This reduces the risk of dizzy or fainting spells.

Your mouth may get dry. Chewing sugarless gum or sucking hard candy, and drinking plenty of water may help. Contact your doctor if the problem does not go away or is severe.

You may need to be on a special diet while taking this medicine. Ask your health care professional how many glasses of water or other fluids to drink each day. Also, ask which foods to include and which to avoid to help keep your urine acidic. Your urine must be acidic for this medicine to work.

This medicine may cause dry eyes and blurred vision. If you wear contact lenses you may feel some discomfort. Lubricating drops may help. See your eye doctor if the problem does not go away or is severe.

Keep out of the reach of children.

Store at room temperature between 15 and 30 degrees C (59 and 86 degrees F). Throw away any unused medicine after the expiration date.