Mithridatism

It is important to note that mithridatism is not effective against all types of poison (immunity generally is only possible with biologically complex types which the immune system can respond to) and, depending on the toxin, the practice can lead to the lethal accumulation of a poison in the body. Results depend on how each poison is processed by the body, ie, on how the toxic compound is metabolized or passed out of the body. In some cases, it is possible to build up tolerance against specific non-biological poisons. For some poisons, this involves conditioning the liver to produce more of the particular enzymes that deal with these poisons (for example alcohol). Another mechanism involves conditioning the target tissues of the poisons. These methods do not work for all non-biological poisons. Exposure to certain toxic substances, such as hydrofluoric acid and heavy metals, is either lethal or has little to no effect, and thus cannot be used in this way at all. Arsenic is a notable exception with some people actually having a genetic adaptation granting them higher resistance which can be replicated with mithridatism. In addition, simple toxins that work through chemical processes that bypass the immune system cannot be dealt with (good example would be the variants of cyanide).

Question: can you build up a resistance to cyanide
Answer: no