Cialis tadalafil : This ED medication works with the same principle as Viagra, but lasts up to 36 hours. Please expect up to 4 to 6 weeks for reimbursement. Make sure to get an estimate of when you can expect your prescription in the mail. In some cases, online ED providers accept health insurance. Follow-up support: Make sure you can get the help you need if questions or concerns arise after ordering. It may be difficult to remain firm despite wanting to have sex. · The highest recommended Viagra dose for treating erectile dysfunction (ED) is mg per day, according to the drug’s manufacturer. Doses of mg or mg would be considered off-label use. Generic Viagra (sildenafil) is an alternative to the branded Viagra drug that can be used for treating erectile dysfunction (ED). It’s now sold by many manufacturers, including online. The maximum dose of Viagra is mg each day. Doses above the maximum dose, such as mg per day, will increase the risk of side effects. And in some cases, this could be serious.