"i am 40 years old. i started taking phentermine 37.5mg 6 weeks ago, and have been doing a 2000 calorie or less diet (because it is hard to eat that much, just not hungry). just went to the doctor today, i have lost 23 lbs. i did experience a little insomnia the first couple of days but i take the pill at 5:30am before work and that seems to help. i sweat a lot for most part of the morning and have a lot of energy but dry mouth is definitely a side effect, but it helps with getting you to drink the amount of water you need to be drinking if you are not a water drinker like me. i do have a significant amount of weight to lose so hopefully the weight loss continues at this rate."