Before using oxybutynin, 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. Before using this medication, tell your doctor or pharmacist your medical history, especially of: active internal bleeding, blockage/slowed movement of the stomach/intestines (such as gastric retention, paralytic ileus), certain bladder problems (urinary retention, bladder outflow obstruction, stress incontinence), glaucoma (narrow-angle), a certain muscle disease (myasthenia gravis), liver disease, high blood pressure, heart problems (such as coronary artery disease, congestive heart failure, arrhythmias), stomach/intestinal disease (such as acid reflux, hiatal hernia, ulcerative colitis, intestinal atony), kidney disease, loss of mental abilities (dementia), enlarged prostate, overactive thyroid (hyperthyroidism), a certain nervous system disorder (autonomic neuropathy), Parkinson's disease. In addition, before you self treat with this medication, tell your doctor if you have any of these signs of a more serious condition: signs of a bladder/kidney infection (such as burning/pain when you urinate, fever, pink/bloody urine), signs of diabetes (such as increased thirst, dizziness/fainting, vision changes, increased urination, wounds that are slow to heal). 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). Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products). This medication may make you sweat less, making you more likely to get heat stroke. Avoid doing things that may cause you to overheat, such as hard work or exercise in hot weather, or using hot tubs. When the weather is hot, drink a lot of fluids and dress lightly. If you overheat, quickly look for a place to cool down and rest. Get medical help right away if you have a fever that does not go away, mental/mood changes, headache, or dizziness. If you are going to have an MRI test, tell testing personnel that you are using this patch. Some patches may contain metals that can cause serious burns during an MRI. Ask your doctor whether you will need to remove your patch before the test and apply a new patch afterward, and how to do so properly. Older adults may be more sensitive to the side effects of this drug, especially drowsiness, confusion, constipation, trouble urinating. 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 unknown if this medication passes into breast milk. Consult your doctor before breast-feeding.