"i began taking phentermine on 12/5/13. at that time i weighed 181 lbs &amp; had 46% body fat. today i weigh 140 lbs &amp; have 33% body fat. i went from a size 14 to a size 6. i still have weight to lose &amp; am continuing to take the medication, but i thought i&#039;d offer my opinion after 5 mos on the medicine. it works very well. having said that, i have had some side effects - dry mouth &amp; insomnia. the dry mouth isn&#039;t all bad. it has forced me to drink tons of water, but the insomnia is difficult. i take 1 37.5 mg pill in the morning, but if i&#039;ve had trouble sleeping for the last few days i might take 1/2 or skip a dose all together. also, the medicine makes me more irritable than normal, but gives me energy to work out."