Pills containing norgestimate or drospirenone (for example, Yasmin�) were associated with a nearly six-fold extra risk. And pills containing cyproterone (for instance, Diane�), had nearly a seven times greater risk. free samples viagra canadian viagra for sale online Cialis, Levitra, and Viagra work by a similar mechanism to cause erections. There are subtle differences in how long the drug works and how quickly it works. Levitra works a little longer than Viagra. They both take effect in about 30 minutes. With Levitra, the effects last for about 5 hours. With Viagra, the effects last approximately 4 hours. Back pain and muscle aches occurred in less than 7% of patients, and usually occurred at 12 to 24 hours after taking tadalafil. The back pain and muscle aches associated with tadalafil were characterized by mild to moderate muscle discomfort in the lower back, buttocks and thighs, often aggravated by lying down. The back and muscle aches resolved in most patients without treatment within 48 hours. When treatment was necessary, acetaminophen (Tylenol) and non-steroidal antiinflammatory drugs (NSAIDs) such as Motrin, Advil, or Aleve were effective. Approximately 0.5% of all the patients using tadalafil discontinued the drug due to back pain or muscle aches.