WESTPORT — Local health and school officials warn Halloween tricksters not to fall victim to a harmful, potentially deadly, narcotic in circulation that could be mistaken for a “treat.”

In an advisory issued for Halloween safety this year, Aspetuck Health District Director Mark Cooper warns that so-called “rainbow fentanyl,” which is increasingly available, can be confused with colorful candies.

Fentanyl-laced pills, resembling candy, have been found elsewhere in boxes of Halloween treats such as SweeTarts, Skittles and Whoppers, according to the statement.

Fentanyl is a deadly synthetic opioid that is being pressed into pills or cut into heroin, cocaine and other street drugs to drive addiction, the health district warns. In addition to pills, the drug is being fashioned into powder and blocks resembling sidewalk chalk.

Supt. of Schools Thomas Scarice on Monday underscored the dangers posed by rainbow fentanyl, issuing a community email to draw attention to the problems outlined by health officials.

The health district also advices that any candy collected by Halloween trick-or-treaters later this week first be inspected at home before being consumed.

Adults are advised to check treats for signs of tampering, such as tears in wrapping, unusual appearance or discoloration and pinholes.

For additional Halloween safety tips from the Aspetuck Health District, click here.