Be careful where you buy your Viagra.

Morrow police have arrested two men on two different occasions and charged them with selling counterfeit versions of the erectile dysfunction drug to an undercover officer.

On Monday, police arrested Patrick Alonzo Applewhite, 41, of Union City. Police allege Applewhite sold 80 pills of what he said was Viagra to an undercover officer on Mt. Zion Circle on Monday afternoon. Viagra is the registered name brand for sildenafil citrate, which doctors prescribe for impotence. Applewhite is being held on $5,000 bond in the Clayton County Jail. His charges include using a computer and cell phone to facilitate the transaction, and with dispensing medication without a license. He also faces charges of possession of a firearm during the commission of a felony. When arrested, Applewhite had a .22-caliber revolver in the glove box of his car.

On Aug. 11, police arrested Evan Cordale Clark, 27, of Stockbridge, after undercover officers bought 30 pills from Clark at a restaurant on Mt. Zion Road. His charges include the sale of a dangerous drug, dispensing medication without a license, and using the Internet to sell the fake drugs. Police say Clark had advertised the Viagra on Craigslist.

Morrow police said samples of the pills have been sent to the trademark holders and to the Georgia crime lab for scientific evaluation.

In both cases, the arresting officers were off duty and working as private investigators for Pfizer, the company that manufactures Viagra.