Wayne Hutchinson says he must spend six days on the sidelines "for concussion" after he suffered a fall at Exeter on Friday.
Hutchinson parted company from Giveaway Glance three fences from home in a mares' handicap hurdle and had to miss the rest of the meeting.
Following a concussive incident, British Horseracing Authority rules state that a rider must immediately be "stood down for a minimum of six days".
Hutchinson had some good rides at Kempton on Saturday as he was due to partner Elgin in the Dovecote Novices' Hurdle and Master Blueyes in the Adonis.
The jockey tweeted: "Unfortunately I've been stood down by Exeter doctor for 6 days for concussion, this was after I successfully completed protocol assessment."
