Vicodin is a controlled drug not only in US, but also in Canada which has somehow similar laws for drug policies as US does. So you wouldn’t be able to buy Vicodin without a prescription in Canada. There are Mexican pharmacies where you can buy Vicodin without a prescription, but when you are coming back into US, the Customs and Border Patrol opens and inspects every package entering from Mexico so you are taking some risks

There are many websites that tell you can buy Vicodin online without needing a prescription. However, you have to be very careful because even if some of these websites would send you real Vicodin pills, buying or selling Vicodin without a prescription is illegal in US.

Even if there are online pharmacies that sell Vicodin because they have a doctor that works for them and writes you a prescription to avoid being in illegality, you’re not always sure that they are legit and they won’t send you other pills that resemble Vicodin. So the best solution would be to visit your doctor and ask for a prescription of Vicodin if you are in pain and really need one.