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U-47700 (Pink)

What is Pink? | How it's sold | Is it dangerous? | Origin of Pink | Pharmacology | DEA schedule | Side effects | Drug testing | Bottom line

Common or street names: Pink, Pinky, U4

What is U-47700 or Pink?

U-47700, also known as “Pink”, "Pinky", or “U4” on the streets, is a potent, synthetic opioid medication developed as a dangerous designer drug. Even small doses can be very toxic or even deadly. Over the past 5 years, reports have surfaced of multiple deaths due to street use of U-47700 or "Pink". Importation into the U.S. is primarily from clandestine chemical labs in China.

How is "Pink" sold?

  • U-47700 has been seized by law officials on the street in powder form and as tablets. Typically it appears as a white or light pinkish, chalky powder.
  • It may be sold in glassine bags stamped with logos imitating heroin, in envelopes and inside knotted corners of plastic bags. Labels on the products may state “not for human consumption” or “for research purposes only”, probably in an effort to avoid legal detection.
  • Some "Pink" products have been sold to mimic bags of heroin or prescription opioid tablets.
  • In Ohio, authorities seized 500 pills resembling a manufacturer’s oxycodone immediate-release tablets, but they were confirmed by chemical analysis to contain “Pink”.
  • U-47700 has also been identified and sold on the Internet misleadingly as a “research chemical” at roughly $30 per gram.

How dangerous is Pink (U-47700)?

Fatalities due to Pink (U-47700) in the United States join the growing incidence of drug overdose deaths due to prescription opioids and synthetic designer drugs like “spice” and “bath salts.” The public using these street or Internet products can never know exactly what is in them, how much, or the degree of toxicity with use.

The Drug Enforcement Agency (DEA) reported at least 46 deaths linked to use of U-47700 that occurred in 2015 and 2016. Fatalities have been reported in Arizona, New York, New Hampshire, Ohio, Texas, and Wisconsin, North Carolina, with multiple reports from state and local forensics laboratories. According to DEA, no other reports of use in the U.S. were found prior to 2015.

Those who abuse U-47700 may be at risk of addiction and substance abuse disorder, overdose and death, similar to abuse of other narcotic substances such as heroin, prescription pain opioids, and designer opioids. This drug may be found in combination, knowingly or unknowingly, with other drugs of abuse bought on the streets such as heroin or fentanyl. It has also been confiscated as a separate product. 

In July 2016, a toxicology case report was published in the Annals of Emergency Medicine that detailed events in which fentanyl and U-47700 were being sold misleadingly as the prescription opioid pain medication Norco (acetaminophen and hydrocodone) on the streets of Northern and Central California. In one patient who presented to the emergency room, naloxone (Narcan) was administered which reversed respiratory depression and pinpoint pupils. After additional chemical analysis, it was found the “Norco” contained hydrocodone, fentanyl, and U-47700.

Reports indicated that U-47700 and prescription opioid fentanyl may have been contained in the drug overdose that led to the death of pop star legend Prince in April 2016. In Utah, two 13-year old boys died in September 2016 reportedly due to use of U-47700 purchased from the Internet.

Where does Pink (U-47700) come from?

These illicit substances appear to originate from overseas, mainly China, and the identity, purity, and quantity of substances in any one product purchased off the street may be unknown. A user may be told the product contains one substance, while in reality it could contain any dangerous chemical.

Pharmacology of Pink (U-47700)

U-47700 (“Pink”) is a novel synthetic opioid agonist with selective action at the mu-opioid receptor.

  • The chemical designation is 3,4-dichloro-N-[2-dimethylamino) cyclohenyl]-N-methylbenzamide.
  • It was originally developed by chemists at Upjohn Pharmaceuticals in the 1970’s as a potent pain reliever for use in surgery, cancer, or painful injuries.
  • Although it was never commercially made available, the patent and chemical details remained available.
  • U-47700 has a similar chemical profile as morphine and other mu-opioid receptor agonists; however, it has been reported by the National Institute of Drug Abuse (NIDA) that Pink is “far more potent than morphine” -- possibly seven to eight times more potent.
  • The strength of the product can never be assured, and may be much stronger, as it is a designer drug made in illegal labs.
  • Animal studies have shown that the analgesic activity of U-47700 was reduced by naltrexone, an opioid receptor antagonist. 

DEA schedule of Pink (U-47700)

In 2018, the DEA issued a Final Order to place U-47700, as well as its related isomers, esters, ethers, and salts into Schedule I of the Controlled Substances Act due to an imminent hazard to public safety and health. Substances in schedule I have a high potential for abuse, no currently accepted medical use, and a lack of accepted safety for use under medical supervision. DEA’s Final Order of scheduling into 21 CFR 1308.11(b) is available in the Federal Register with details on threats to public safety.

In 2016, U-47700 had been placed in Schedule I temporarily to determine its final status. Temporary emergency scheduling of dangerous illicit drugs is one tool the DEA uses to help restrict potentially fatal and new street drugs. Scheduling usually last at least 24 months, with a possible 12-month extension if the DEA needs more time to determine if the chemical should remain permanently in schedule I. According to the Federal Register at that time, there were no current investigational or approved new drug applications for U-47700 which might hinder its placement in Schedule I.

Prior to the DEA’s emergency scheduling, several states had already outlawed the drug under emergency orders, including Florida, Ohio, Wyoming and Georgia.

Pink (U-47700) side effects and toxicity

U-47700 or “Pink” is abused for its opioid and narcotic-like effects, and is swallowed, snorted or injected. It is one of many synthetic designer drugs. Pink effects as reported by users are similar to the effects of opioids, which might include:

  • euphoria, feeling "high, and other psychoactive effects
  • sedation, relaxation, numbness
  • potent analgesia
  • severe, possibly fatal respiratory depression
  • pinpoint pupils
  • constipation
  • itching
  • drug tolerance, dependence, addiction
  • seizures
  • psychosis
  • fatal overdose
  • potent analgesia

Does Pink show up on drug tests?

Currently, U-47700 is not included in standard workplace drug screens in the U.S.; however, forensics or medical laboratory testing may request to identify U-47700 through analytical techniques such as gas chromatography and mass spectrometry (GC-MS).

Learn More: Drug Testing FAQs

Bottom line on Pink

U-47700, known on the streets as Pink or U4, is a dangerous designer drug exported from illegal labs in China to the U.S. It has effects like a strong opioid analgesic, and have been reported to be 7 to 8 times more potent than morphine. U-47700 is now illegal in all forms, and the DEA has placed the substance into Schedule I of the Controlled Substances Act, due to an imminent hazard to public safety and health.

Authorities in many U.S. cities have reported that Pink is sold on the streets or over the Internet, often promoted as a prescription opioid like Norco or as heroin. Many of these products, when confiscated and analyzed, have contained this potent designer drug, as well as fentanyl.

Clusters of overdoses and deaths in U.S. cities were reported in 2015-2017 with Pink; some in children. According to one case report, the use of naloxone (Narcan) in an emergency setting reversed the effects of U-47700. Emergency physicians should contact their local poison control center, medical toxicologist or public health department in cases where there is a reasonable suspicion of ingestion of designer drugs to help protect the surrounding community. Special lab analysis may be needed to identify drugs like Pink.

The public should be aware that drugs obtained on the street, even though they look like an authentic prescription medication, may be fake and deadly. Don't take any prescription drug -- legal or otherwise -- unless it is written specifically for you by a doctor and is dispensed from a reliable pharmacy.

See Also


  1. Final Order: Placement of Butyryl Fentanyl and U-47700 Into Schedule I. United States Drug Enforcement Agency (DEA). Federal Register Volume 83, Number 77 (Friday, April 20, 2018). Accessed June 30, 2019.
  2. Rudd RA, et al. Increases in Drug and Opioid Overdose Deaths — United States, 2000–2014. Morbidity and Mortality Weekly. Centers for Disease Control and Prevention (CDC). Accessed June 30, 2019 at
  3. DEA Temporarily Bans Synthetic Opioid U-47700 ("Pink"), Linked to Nearly 50 Deaths. National Institute on Drug Abuse (NIDA). November 15, 2016. Accessed November 25, 2016 at
  4. DEA Schedules Deadly Synthetic Drug U-47700. November 10, 2016. Accessed June 30, 2019 at
  5. BBC News. Prince death: Powerful drugs found in singer's home 'were mislabelled'. 21 August 2016. Accessed June 30, 2019 at
  6. Armenian P, et al. Fentanyl and a Novel Synthetic Opioid U-47700 Masquerading as Street “Norco” in Central California: A Case Report. Published online: July 26, 2016. Accessed June 30, 2019 at
  7. Fentanyl-Laced 'Norco' Is Lethal, Report Warns. July 29, 2016.
  8. U-47700: Everything You Need to Know About Deadly New Drug. Rolling Stone Magazine. Accessed June 30, 2019 at
  9. Synthetic opioid nicknamed ‘pink’ blamed for deaths of two 13-year-old Utah boys. The Washington Post. Accessed June 30, 2019 at
  10. Kroll D. Prince's Death From Fentanyl May Have Been Due To Counterfeit Generic Drugs. Forbes. Accessed June 30, 2019 at
  11. A dangerous mix of opioids called ‘gray death’ is causing overdoses in parts of the US. Science. Business Insider. May 8, 2017. Accessed Jan 30, 2020 at




Further information

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