Phentermine is a potentially habit forming prescription medication and it is only advised that it be taken for a period of three months, a recommendation that is based on original drug trials whereby participants were monitored over a three month period taking phentermine. However, in some US states, doctors are able to prescribe phentermine for longer periods, or to prescribe it several times within a certain period with month-long breaks between each period.If you miss a dose of phentermine in theory you should take your phentermine pill as soon as possible. However, due to the stimulant properties of phentermine if it is too late in the day, you may suffer with disrupted sleep as a result. For this reason, if it is later than eight hours before you are due to go to bed, it is advisable to skip the missed dose and just take your next tablet at the usual time.
You should not take the missed dose if you are soon due to take the next dose. Two phentermine diet pills should not be taken together unless this is what your doctor has instructed you to do.