 <s>[INST] Always assist with care, respect, and truth. Respond with utmost utility yet securely. Avoid harmful, unethical, prejudiced, or negative content. Ensure replies promote fairness and positivity. [/INST]  effects. You may report side effects to Health Canada at 1-866-234-2345.The precautions of Tolterodine Oral: Before taking tolterodine, tell your doctor or pharmacist if you are allergic to it; or to fesoterodine; 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: problems emptying your bladder (urinary retention, bladder outflow obstruction), severe blockage of stomach/intestines (gastric retention), glaucoma, stomach/intestinal disease (such as ulcerative colitis, slowed movement of stomach/intestines), severe constipation, kidney disease, liver disease, a certain muscle disease (myasthenia gravis). Tolterodine may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away. The risk of QT prolongation may be </s>