If your dose is different, do not change it unless your doctor tells you to do so. These medicines all work well for ED. If you are taking sildenafil to treat PAH, you will probably take sildenafil three times a day with or without food. Tips for Successfully Obtaining a Free Sample of Viagra Pack by Mail There are a few suggestions to remember to improve your chances of success when requesting a free Viagra sample via mail. Side Effects Free Viagra samples may come with possible side effects, including flushing, indigestion, heartburn, diarrhea, insomnia, tingling in the limbs, muscular aches, sensitivity to light, and headaches. Oral medicine for ED also might not be safe or work well if you have: Very low blood pressure, called hypotension, or uncontrolled high blood pressure, called hypertension. · Initial dose: 50 mg orally once a day, as needed, 1 hour prior to sexual activity. Maintenance: 25 to mg orally once a day, as needed, 1 hour prior to sexual activity. Comments: This drug may be taken anywhere from 30 minutes to 4 hours before sexual activity. Use: Treatment of erectile dysfunction. A Florida man has been charged with several felonies and a misdemeanor after police say he threatened a CVS pharmacy, asking for “all bottles” of Viagra, Adderall and other drugs. Maria Hudson. 4 hrs. ago. Anna Nelson. 6 hrs. ago. David Muldon. 8 hrs. ago.