An increasingly popular synthetic opioid known as Pink is being sold online, according to NBC News. Only four states—Florida, Ohio, Wyoming and Georgia—have banned the drug, also known as U-47700.

Pink is eight times stronger than heroin, the article notes. The drug, along with other synthetic opioids, is being shipped into the United States from China and other countries.

The Drug Enforcement Administration (DEA) told NBC News it is aware of confirmed deaths associated with the drug in New Hampshire, North Carolina, Ohio, Texas and Wisconsin. Last month the agency gave notice of its intent to classify the drug temporarily as a Schedule I substance under the Controlled Substances Act. The temporary ban gives the DEA three years to research whether the drug should be permanently controlled.