Phentermine is a controlled substance and it has become illegal to sell phentermine on the internet now. So most likely any phentermine that you buy anywhere on the internet will be fake. Do it the right way and get a prescription from a doctor who can monitor you while on the medication. I have included an article about this that I found off of a reliable website stating that it IS ILLEGAL to sell phentermine the doctor that prescribes the phentermine MUST be able to provide the patient with a physical exam done by the prescribing doctor himself.
Federal law prohibits buying controlled substances such as narcotic pain relievers (e.g., OxyContin®, Vicodin ®), sedatives (e.g., Valium®, Xanax®, Ambien®), stimulants (e.g., phentermine, phendimetrazine, Adderall®, Ritalin®) and anabolic steroids (e.g., Winstrol®, Equipoise®) without a valid prescription from your doctor. This means there must be a real doctor-patient relationship, which by most state laws requires a physical examination. Prescriptions written by "cyber doctors" relying on online questionnaires are not legitimate under the law.
Buying controlled substances online without a valid prescription may be punishable by imprisonment under Federal law. Often drugs ordered from rogue websites come from foreign countries. It is a felony to import drugs into the United States and ship to a non-DEA registrant.
Buying drugs online may not be only illegal, but dangerous. The American Medical Association and state boards of medicine and pharmacy have all condemned the practice of cyber doctors issuing online prescriptions as unacceptable medical care. Drugs delivered by rogue websites may be the wrong drugs, adulterated or expired, the wrong dosage strength, or have no dosage directions or warnings.
DEA is targeting rogue online pharmacies for prosecution and shutting down these illegal websites. See the results of one such investigation, Operation Cyber Chase, at www.usdoj.gov/dea/pubs/pressrel/pr042005.html
How to spot a rogue pharmacy: www.DEAdiversion.usdoj.gov/faq/internetpurch.htm
To report illegal prescription drug sales and/or rogue pharmacies operating on the Internet call the anonymous Pharmaceutical Drug Abuse Hotline: 1-877-RxAbuse (1-877-792-2873)