Men may take it socially with other drugs, rather than for treatment of a medical condition. Think headaches, upset stomach, blue-tinted vision, flushing, diarrhea, difficulty sleeping or dizziness. Medicines that block an enzyme called CYP3A4. You can take it in a small dose daily or in a larger dose as needed. Your doctor or other health care professional can recommend one for you based on these factors, other health conditions you have and any other medicines you take. These include itraconazole Sporanox, Tolsura , ketoconazole Extina, Ketozole, others and ritonavir Norvir.Additionally, medications like Viagra can cause priapism — an erection lasting over 4 hours that can result in permanent damage. If this happens, you’ll need to get medical . Never order medicines from an online pharmacy that doesn’t list its phone number and physical address, has prices that seem too good to be true, or tells you that no . Cost Pregnancy Birth control needs Breastfeeding For professionals Drug Images What is Viagra? Viagra is a brand-name prescription drug that’s approved to treat erectile .