The 25-year-old Reid, however, could be released earlier to a less restrictive facility if he is accepted into a drug-treatment program, Montgomery County District Attorney Risa Vetri Ferman said.
Reid is already serving time in the county jail for a heroin-fueled car crash that injured a motorist. Jail officials say he smuggled the pills inside when he surrendered last fall, just before his guilty plea to crash-related charges.
"While we understand that some defendants, this one in particular, have substance-abuse issues, he still committed a very serious offense," Ferman said. "We need to take a very hard line on crimes like this to make sure that prison authorities can maintain order."
Reid once told probation officers that he was an addict who had gotten a thrill selling drugs in inner-city Philadelphia.
He entered his plea Wednesday before Judge Steven O'Neill, who last year questioned Andy and Tammy Reid's supervision and compared their home to a "drug emporium."
Another son, Britt Reid, 23, is in a county drug-court program after pleading guilty that same day to separate drug and gun charges.
The Reids later spoke publicly of their many attempts to get their sons in treatment, and the toll it had taken on their family. They have three other children.
Garrett Reid's formal sentencing on the smuggling charge is on hold while he is considered for the treatment program. He is serving a sentence of up to 23 months on the earlier charges.
Defense lawyer Timothy Woodward did not return phone calls Wednesday seeking comment.