If you use prescription painkillers or designer drugs, it’s about to get much tougher for you to join the military.

The Pentagon plans to quickly expand the number of drugs in its test panel for recruit hopefuls, a nod to the prescription-painkiller epidemic and recent popularity of synthetic pot.

What’s being added to the list: heroin, codeine, morphine, hydrocodone, oxycodone, hydromorphone, oxymorphone and a number of synthetic cannabis-like drugs and benzodiazepine sedatives.

Now applicants will be screened for the same 26 drugs for which active-duty troops are regularly tested.

The new policy is scheduled to start April 3, the Defense Department said Thursday.

The Pentagon, in a news release, pegged the change to “the level of illicit and prescription medication abuse among civilians, as well as the increase in heroin and synthetic drug use.”

The expanded screening is expected to trip up about 450 people a year, the Pentagon estimated. Of the 279,400 applicants per year, about 2,400 test positive for the drugs that were already in the protocol.

Applicants who fail the test can reapply. Anyone who fails twice is permanently disqualified for military service.