Jones, a starting strong safety, was suspended Friday for the first four games of the regular season. He said he took a supplement that caused the violation.
Defensive end Dion Jordan was suspended last month for the first four games after testing positive for a prohibited stimulant.
Like Jordan, Jones is eligible to participate in all preseason practices and games. That included Friday night's exhibition opener at Atlanta.
''I worked closely with the union to investigate what happened, and I learned that a supplement I took caused the positive test,'' Jones said in a statement released by the Dolphins. ''I deeply regret not investigating the supplement carefully before I took it, and I will never again take a supplement without having it checked. I am very sorry for the effect of my mistake on my teammates and coaches.''
Jones, a fifth-year pro, started every game the past two seasons and finished second on the team in tackles last year.
The suspension is without pay. Jones will be eligible to return to the active roster following the Dolphins' Sept. 28 game against Oakland.
''I was very disappointed when we found out about Reshad's suspension,'' coach Joe Philbin said in a statement. ''When we talked to him, Reshad pledged to learn from this situation.''
Jones will likely be replaced in the starting lineup by Jimmy Wilson, a fourth-year pro with eight career starts.
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