As with sildenafil, a high-fat meal or alcohol keep the body from absorbing it as quickly. Generic versions of sildenafil, vardenafil and tadalafil are available. Medicines that you take by mouth are called oral medicines. Dosage and Administration The suggested Viagra dosage is 50 mg, given about an hour before sexual activity. When oral medications might not be safe Check with your health care team before you take any medicine for erectile dysfunction. Free Viagra samples are frequently offered for a brief period of time and can be requested via online forms or by getting in touch with the business. Viagra generic variants are frequently more affordable than name-brand drugs.The four main medicines taken by mouth for erectile dysfunction are: Avanafil (Stendra). Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called .  · 2. Rex MD – Free Viagra Samples. Rex MD is a men’s health-focused telemedicine service. They provide free prescription pharmaceutical samples for erectile .