Victorian jockey Patrick Holmes has been sidelined for four months after testing positive to an unnamed banned substance.

The 30-year-old returned a positive urine sample at a meeting at Swan Hill in early June.

He was stood down from all riding and handling duties on June 27 and won't be allowed to return to racing until October 27.

His suspension was confirmed at Bendigo on Friday and published online on Tuesday.

"Stewards ... took into account Patrick Holmes' forthright evidence and written evidence tendered that he has and is currently receiving counselling regarding his personal circumstances," the stewards report says.

Stewards have not named the substance involved but banned Holmes under AR81A, which covers alcohol and other drugs.

The jockey will be allowed to resume riding trackwork as soon as he returns a clean sample.

Holmes has raced 305 times this season for 21 wins.