Erectile dysfunction is a very common medical condition that can affect men of any age or background. Fortunately, Pfizer created a drug called Viagra that works to help men achieve longer and harder erections during sexual intercourse. As long as the drug is taken in combination with sexual stimulation, the results can be very impressive. If you are wondering how long the Viagra will remain in your system, there is no set answer; the results vary according to each individual. However, the drug generally lasts for 3 to 4 hours for most men. However, it is important to note that various factors may affect how long the Viagra will stay in your system. For example, taking certain medications at the same time may decrease or increase the length of time the drug remains active. Viagra often remains in the system longer for men older than 65. That is why doctors usually prescribe a lower dosage for older individuals, especially if it is their first time trying the erectile dysfunction drug.