Rc suppressants (Rc抑制液, Rc yokuseieki) are the drugs used to suppress the activity of the kakuhou. They were specially made by the CCG's Medical Department, designed for the sole purpose of inhibiting the activity of a ghoul's Rc cells. However, they can also be applied on humans as well since it is the only known treatment for Rc cell over-secretion disease (ROS). While available to the general public for this purpose, their cost makes them nearly impossible for most to afford. However, it is only made available for distribution by special affiliates of and from the CCG.
Mostly seen in fluid form, in a solid light color. They are usually stored in tubular containers, in an airtight and sterile environment. In a liquid state, Rc suppressants carry a distinct odor. To a ghoul, it is described as a unforgettable pungent odor that fills the nostrils.
When injected in fluid form, Rc suppressants are usually delivered via a hypodermic needle into the muscle. Upon injection, the drug is absorbed fairly quickly, a trait usually attributed to a drug's unknown chemicals. For Rc suppressants, ingredients include an Rc solution. Injected drugs are usually preferred as they allow the full effects of a drug to be experienced.
The effects to ghouls include slower regeneration, kagune impairment — even the capability of preventing its use at all — and vulnerability to mundane items such as knives; grogginess has been observed but it is unconfirmed to be either an intended symptom or a common side effect. When Rc cell activity is suppressed, it may cause an increase in melanin production that causes changes in hair color. The effects of Rc suppressants do eventually wear off, but the specific time before this occurs is unknown.
The CCG uses Rc suppressants as a means to subdue a ghoul rather than to exterminate. Cochlea uses it for their ghoul prisoners, to weaken them for interrogation and/or as a measure for caution. Another known use which takes advantage of the ghoul's newfound vulnerability is for surgery or dissection.