As with most medications, some potential side effects come with using phentermine. Phentermine has both common side effects as well as rare side effects. Some may be more severe than others may.
Some side effects that may occur are not a threat to your overall health and may not require medical attention. As your body adjusts to the treatment, you may find some symptoms and side effects of phentermine disappearing after a while.
However, you should always contact your medical physician with any questions or concerns while on phentermine, or if these symptoms become inconvenient and affecting your daily life for long periods at a time.
Consuming alcohol while on phentermine can increase some side effects.
You should seek urgent medical care if you experience an allergic reaction to phentermine.
- Wheezing and/or trouble breathing
- Tightness in the chest
- Swelling of your face, tongue, lips
- Swelling of the throat
Be sure to consult with your doctor if any of these common symptoms apply to you while on the prescription:
- Dizziness or headache
- Trouble sleeping or showing signs of insomnia
- Decrease or increase in sexual activity
- Having an unpleasant taste in your mouth, dry mouth
- Upset stomach, constipation or diarrhea
- Lack of desire to exercise
- Shaking or trembling of the hands, feet, arms or legs
You should call your doctor immediately if you experience these serious side effects:
- Unusual behavior or thoughts
- Random mood swings or confusion
- Quick and pounding heartbeats
- Pain in the chest and the sensation that you might pass out
- Breath seems short even when using little exertion
- Swelling within your ankles or feet
- Very high blood pressure
Other side effect information
You should not take phentermine if you are pregnant or nursing.
If you are on other medicines such as stimulants or drugs that make you hyperactive or restless, phentermine may worsen those effects. You should check with your doctor if you are currently on any weight loss pills already or medicines that treat attention deficit hyperactivity disorder (ADHD).
Other medicines that may interact with phentermine are:
Citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine or sertraline
Overdosing on Phentermine
Overdosing on this drug can prove to be fatal. If you find that you have overdosed on phentermine, you should seek medical attention immediately or call the Poison Help line at 1-800-222-1222.