Symbiote-masking drug
From The Stargate Omnipedia
A Goa'uld designed compound capable of masking the presence of a Goa'uld symbiote from other Goa'uld, Tok'ra, Jaffa, or others capable of sensing it. Taken by injection, the drug essentially allows an undercover Goa'uld agent to go undetected.
The symbiote-masking drug was given to the Goa'uld-possessed Kianna Cyr by the System Lord Baal when she went to work with Jonas Quinn on the planet Langara, in case a symbiote-detecting presence should threaten her mission to uncover Anubis's special interest in the planet.
KEY EPISODE
Fallout - SG-1 discovers that Kianna is a Goa'uld, and has been taking a drug to mask the presence of her symbiote from Carter and Teal'c.