Is xenical effective dapoxetine belongs to a class of selective serotonin reuptake inhibitors (SSRIs). This short-acting inhibitor is used to treat premature ejaculation in men. The recommended dose of Cialis is 20 mg it should be taken at least 16 minutes before the sexual activity. The effect persists for 36 hours. Take Cialis once daily and do not exceed the recommended dose. If you think you have used too much of this medicine seek emergency medical attention right away. The symptoms of overdose usually include chest pain, nausea, irregular heartbeat, and feeling light-headed or fainting.