Why am I tired on Phentermine?
Medically reviewed by Drugs.com. Last updated on Nov 3, 2020.

Official Answer
by Drugs.comFatigue or tiredness can come as a result of sleepless nights or following a period of over-stimulation, however, adverse effects of phentermine also include drowsiness, fatigue, and reduced energy levels. If you’re feeling fatigued or lacking in energy while taking phentermine and the problem persists, you should consult your doctor as it may be that you have an undiagnosed medical condition.
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Drug Information
- Phentermine Information for Consumers
- Phentermine Information for Healthcare Professionals (includes dosage details)
- Side Effects of Phentermine (detailed)
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