Valtrex is the trademark name of an anti-viral drug, Valaciclovir or valacyclovir marketed by GlaxoSmithKline. Its chemical structure is given in the diagram taken from Wikipedia - Valaciclovir under the GNU Free Documentation License (GFDL).
Genital herpes simplex (treatment and prophylaxis)
Prevention of CMV disease following organ transplantation
Reduction of HSV transmission from people with recurrent infection to uninfected individuals
Valtrex is a prescription drug, which means you will need a doctor's prescription to purchase it. If you cannot find a doctor to do that for you, according to Valtrex Prescriptions, they have a network of board-certified physicians from which you can choose to communicate confidentially physician, and after consultations, you may get that prescription needed to enable you to purchase any prescription drugs.