When you’re taking Phentermine, you should go to the emergency room if you experience any of the side effects listed below:

I) Allergic Reaction:

a. difficulty breathing

b. partial closing of the throat

c. lips, face, or tongue swell

d. hives (rash of red blotches)

e. abnormal heartbeat

f. extremely high blood pressure

g. extremely painful headache

h. abnormally blurry vision

i. hallucination

j. strange behavior

k. confusion

If you notice any of these less dangerous side effects of Phentermine, it is still alright to keep using your Phentermine prescription. However, you must make sure to let your doctor know about them:

II) Less serious possible side effects of Phentermine:

a. restlessness

b. shaking/tremors

c. nervousness

d. unusual levels of stress/anxiety

e. mild headache

f. dizziness

g. insomnia (trouble getting to sleep)

h. dry mouth

i. bad taste in your mouth

j. constipation

k. diarrhea

l. impotence

m. changes in sex drive

You should know that Phentermine can be addictive. This is probably due to the fact that your body gets used to the levels of neurotransmitters in the nervous system that are adjusted by Phentermine. I’m not sure about it though, since I’m no expert. That’s just what amateur (and brief, I must say) research has led me to believe. Anyway, you might grow to depend on it in both
body and mind.

As with any medication that you’ve become even slightly addicted to, you could experience unpleasant side effects when withdrawing yourself from Phentermine use during at least several weeks. Before you stop taking your Phentermine prescription, please have a talk with your physician/doctor to see what the plan should be for gradual withdrawal.

In addition to the notes above, you should keep in mind that other side effects of Phentermine could occur, which have not been listed on this site. If you notice anything strange happening, please alert your doctor.