It may be difficult to remain firm despite wanting to have sex. Apart from treating ED, Cialis is also prescribed for benign prostatic hyperplasia, a condition characterized by an enlarged prostate. Its effects often last for 4 to 5 hours. However, others work on a cash-pay basis and don’t partner with insurance companies. This medicine works best when you take it on an empty stomach an hour before sex.Side Effects. Headache, stomach upset, back pain, muscle pain, stuffy nose, flushing, or dizziness may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly. To. Published on October 18, warning This article is no longer being updated and some information may not be current. Visit the GoodRx Healthhomepage for our latest articles. We have good news for you: generic Cialis, used to treat erectile dysfunction (ED)and enlarged prostates, just hit pharmacies. Best Low Cost: GoodRx Fastest Delivery: Blink Health: Sesame Sign Up Now Key Specs Cost: Consultation prices vary based on the prescriber; $5 generic prescriptions Medical Consultation Required: Yes Medications Prescribed: Viagra, Cialis, sildenafil, tadalafil Generic offered: Yes Why We Chose It.