That depends. In the United States, each state sets the parameters for prescriptions. This means that states decide how long a prescription can be refilled. For example, in Ohio a non-controlled prescription must be initially filled within 6 months or it expires. If it is filled the first time within the six months, it is then good for one year from the date written. Example: You get a prescription for fexofenadine (Allegra, generic) written on 11-13-2006. You must fill it for the first time before 5-13-2007 or it expires. Say you fill it on 1-3-2007, it is then refillable until 11-13-2007. In Ohio, controlled substances (e.g. Vicodin, etc.) are only valid for a total of 6 months, no exceptions Check with your local pharmacist or State Board of Pharmacy (or Regulatory Body) for the complete answer in your state or country.
Depends............if it is a long term on going medication, it will be good for a year, at which time the doctor will no longer refill it until he sees you again. If you mean, if he writes it and you do not fill it, have no idea. Call the pharmacy.