World Anti-Doping Agency (WADA) chairman Dick Pound says cycling's image is "in the toilet".
Pound warned the sport that it risks losing competitors unless it acts after the pre-Tour de France doping scandal.
"The image of your sport and flagship event is in the toilet," Pound told Five Live's Sportsweek.
"You've got to do something about it or the risk is that your sport will be ignored by everybody, marginalised by others and it won't be sport any more."
In all, 13 riders were withdrawn by their teams the day before the Tour de France started on Saturday after being on a list of 56 implicated in a Spanish doping investigation.
The 13 included two of the sport's leading stars and pre-Tour favourites, German Jan Ullrich and Italian Ivan Basso, who have both protested their innocence.
Cycling generally has been pretty close to clinical denial about the extent of the problem
But Pound believes the knock-on effect of such negative publicity could affect the numbers taking up cycling.
"Under these circumstances, if I had a child who showed some potential in this, I'd say 'it appears that if you want to get to the top of this sport you've got to use all these drugs, so why don't we find some other sport for you'," he added.
"I think cycling generally has been pretty close to clinical denial about the extent of the problem in this sport and now this is open for the entire world to see.
"I think if they resolve to actually do something about it they have a chance to take some steps that they haven't been able to in the past."
The latest doping investigation is the biggest scandal to hit the sport since the Festina affair during the 1998 Tour de France, which brought to light the use of the blood-boosting drug erythropoietin (EPO) among riders.
Seven-times King of the Mountains winner Richard Virenque was handed a nine-month ban after admitting to doping offences.
Last year's Tour of Spain winner Roberto Heras was also banned for two years in November after testing positive for EPO during the race.