The symptoms of nicotine overdose are clearer indicators of what is happening in your body than the symptoms of withdrawal. This is because nicotine overdose has been studied a fair bit. Nicotine withdrawal has not been studied nearly as much. What has been studied a lot is cigarette withdrawal which is a different thing – it includes no longer inhaling a few thousand chemicals, not just nicotine.
As of April 2019, CBD extracted from marijuana remains a Schedule I Controlled Substance, and is not approved as a prescription drug, dietary supplement, or allowed for interstate commerce in the United States. CBD derived from hemp (with 0.3% THC or lower) was delisted as a federally scheduled substance by the 2018 Farm Bill. FDA regulations still apply: hemp CBD is legal to sell as a cosmetics ingredient, but despite a common misconception, because it is an active ingredient in an FDA-approved drug, cannot be sold under federal law as an ingredient in food, dietary supplements, or animal food. It is a common misconception that the legal ability to sell hemp (which may contain CBD) makes CBD legal.
Cannabidiol has antipsychotic effects. The exact cause for these effects is not clear. But cannabidiol seems to prevent the breakdown of a chemical in the brain that affects pain, mood, and mental function. Preventing the breakdown of this chemical and increasing its levels in the blood seems to reduce psychotic symptoms associated with conditions such as schizophrenia. Cannabidiol might also block some of the psychoactive effects of delta-9-tetrahydrocannabinol (THC). Also, cannabidiol seems to reduce pain and anxiety.