Before taking flavoxate, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details. This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: stomach/intestinal blockage (e.g., pyloric/duodenal obstruction, ileus), bleeding from the stomach or intestines, bladder blockage. Before using this medication, tell your doctor or pharmacist your medical history, especially of: heart problems (e.g., fast/irregular heartbeat, heart failure), a certain eye condition (glaucoma), kidney problems, a certain muscle disease (myasthenia gravis), enlarged prostate gland, stomach/intestinal problems (e.g., infection, acid-reflux disease, chronic constipation, ulcerative colitis), overactive thyroid (hyperthyroidism). This drug may make you dizzy or drowsy or blur your vision. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis). This medication can cause decreased sweating. To reduce the risk of a serious reaction to too much heat (heatstroke), avoid becoming overheated in hot weather, saunas, or during exercise or other strenuous activities. Older adults may be more sensitive to the side effects of this drug, especially dizziness (more likely when standing up), drowsiness, constipation, trouble urinating, or confusion. Dizziness, drowsiness, and confusion can increase the risk of falling. During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor. It is not known whether this drug passes into breast milk. Consult your doctor before breast-feeding.