Phentermine 37.5 mg is a prescription appetite suppressant used short-term (a few weeks) for weight loss in obese adults. The standard dose is 37.5 mg once daily, taken before breakfast or 1-2 hours after, promoting average losses of 3-7 kg in studies when combined with lifestyle interventions. Buying online requires a valid prescription from a licensed provider, as it's a controlled substance; seek FDA-approved pharmacies for low, authentic prices to avoid counterfeits and risks like increased heart rate or insomnia. Consult a doctor before use, especially with heart conditions.