A logo reading DEA Special Agent is pictured in the Office of the US Drug Enforcement Administration (DEA) in May 2019 in New York City.
CNN  — 

The order from an online “pharmacy” was for oxycodone, a powerful narcotic used to treat pain.

The pills looked exactly like the real things, their true contents masked by meticulous counterfeiting. Days after receiving her online shipment, the woman who ordered them was dead from acute fentanyl poisoning.

The incident is recounted in a new public safety alert from US Drug Enforcement Administration investigators, who warn about a rise in illegal, typically foreign-based online stores that are allegedly targeting American consumers with deceptive practices.

“These companies operate illegally, deliberately deceiving American customers into believing they are purchasing safe, regulated medications when they are actually selling fake, counterfeit pills made with fentanyl or methamphetamine,” the DEA said, noting that the fake pharmacies often use US website addresses and are professionally designed.

And rather than selling products manufactured by reputable pharmaceutical companies, the DEA said, “Many of these sites purport to be legitimate, U.S. based or FDA approved sites, but are actually working with drug traffickers to fulfill online orders with fake pills.”

Authorities say there are numerous red flags that can alert consumers to a possible scam, including sites that sell drugs without requiring a valid prescription, those with prices listed in foreign currency, site with no proof of valid state and federal licensing, and the arrival of damaged packaging in a foreign language or pills with no expiration dates.

In a similar warning this month from the US Centers for Disease Control and Prevention, authorities said suspicious online pharmacies have also been known to “offer deep discounts or prices that seem too good to be true.”

Fake pharmacy websites identified by DEA agents include many with generic names, such as pharmacystoresonline.com, careonlinestore.com, orderpainkillersonline.com and USAmedstores.com. Those sites now redirect visitors to a message indicating that the domain has been seized by US authorities.

“If you have purchased alleged medication from any of these websites, you should immediately stop using it and contact your local DEA office” or report the incident online, the DEA warned.

In addition to publicly alerting consumers about the dangers of fake online pharmacies, federal agents have been working behind the scenes to disrupt and dismantle deadly trafficking operations.

Get CNN Health's weekly newsletter

Last month, the US Justice Department announced criminal charges against 18 defendants alleged to have operated fake online pharmacies after an investigation by the DEA and the Homeland Security Investigations agency.

Officials say the group, with members based in the US, India and the Dominican Republic, allegedly distributed millions of counterfeit pharmaceuticals online, including fake pills that killed at least nine unsuspecting customers.

If convicted, all 18 defendants face up to life in federal prison, DOJ said.

“These individuals sold millions of dangerous fake pills to victims in every U.S. state and the District of Columbia,” DEA Administrator Anne Milgram said in a statement. “The defendants did this to make money by driving addiction with deadly, highly-addictive fentanyl. The DEA is relentlessly focused on saving lives by finding these criminal networks and shutting them down.”