A phone or video consultation is sometimes required for legal purposes. That’s not to say there aren’t just as many illegitimate sites. Psychological factors like stress, depression, or anxiety can also contribute. Never purchase ED medications from a site or service that doesn’t require a prescription and medical documentation. If you have an erection that lasts more than 4 hours, get medical help right away. Use the oral syringe provided with your medication to measure and take your dose. The generic versions are just as effective and much less expensive.Does the price of sildenafil vary based on strength or what it’s prescribed for? The price you’ll pay for sildenafil may vary based on the strength and form of the drug your doctor . Does Viagra’s average price vary based on which strength I take (25 mg, 50 mg, mg)? It’s possible for Viagra’s cost to vary by a few dollars based on the strength you take.  · You can take the drug 30 minutes to 4 hours before you anticipate sexual activity. Based on how well you respond to this dosage and any side effects you have, your doctor may either increase your.