The former Liverpool goalkeeper spent four years at Anoeta from 2001 to 2005 and says he saw squad members receiving injections on a frequent basis.
“Of course at Real Sociedad there were players who received intravenous injections before and after games,” he told Voetball.
“I never saw or noticed anything unusual [about an injection] that someone would have received.”
Former Real Sociedad president Ianki Baidola recently claimed the club bought banned substances for six years between 2001 and 2007.
The-then chairman Jose Luis Astiazaran has denied the club were ever involved in any wrong-doing and Westerveld feels the intravenous injections never made him feel as though he was cheating in any way.
“I never noticed anything that would improve my performance particularly,” he said.