Small case studies in pregnant women with PAH indicate a low risk of harm, though caution is warranted. The most common side effects of VIAGRA: headache; flushing; upset stomach; abnormal vision, such as changes in color vision such as having a blue color tinge and blurred vision; stuffy or runny nose; back pain; muscle pain; nausea; dizziness; rash. There are no antidotes available for sildenafil. A small placebo-controlled week study performed on men with erectile dysfunction used the Self Esteem and Relationship SEAR questionnaire to assess the impact of sildenafil treatment on patients. Medicines that you take by mouth are called oral medicines.Compare prices and print coupons for Viagra (Sildenafil) and other drugs at CVS, Walgreens, and other pharmacies. Prices start at $ Buy online with free shipping. Adelaide Apothecary. Free shipping $ please call or email us at or ada@ so that we can provide you with the services you require through. 1 day ago · If you’re prescribed Viagra, you can purchase it in doses of 25, 50, or milligrams (mg). Hims recommends taking Viagra anywhere from 30 minutes to 4 hours before sexual activity. Sildenafil (Viagra) is a medicine used to treat erectile dysfunction (ED, also called impotence). Sildenafil works by helping to relax the blood vessels in the penis, allowing more blood to flow in and cause an erection. You should take sildenafil about an hour before planned sexual activity, so it has time to work.