Never take an extra dose to make up for a forgotten one. Medicines that you take by mouth are called oral medicines. Sildenafil Viagra. Box , Mission, KS If your pharmacy does not participate, you may be able to submit a request for a rebate in connection with this Savings Offer. How to take tablets Swallow tablets whole with a drink of water or juice but not grapefruit juice. How to take liquid If you or your child are taking sildenafil as a liquid, 1ml is usually the same as taking a 10mg tablet, but it’s important to always check the medicine label. How oral medicines differ Each oral medicine for ED has a slightly different chemical makeup.Cialis lasts up to 36 hours in the body, while Viagra lasts 4–6 hours in the body. Both are taken 30 minutes before sex. Cialis can cause limb pain, while Viagra can cause vision change, rash. AdHazte con las últimas tendencias en moda de mujer, hombre e infantil. Rx Medication.  · Follow all directions on your prescription label and read all medication guides or instruction sheets. Revatio is usually taken three times each day, about 4 to 6 hours apart. Viagra can help you have an erection when sexual stimulation occurs. An erection will not occur just by taking a pill. Follow your doctor’s instructions.