"at one point, was used by doctors and dentists, sometimes as a numbing agent before extracting a tooth. it was not until much later that this drug's problematic characteristics were recognized."

cocaine

Explanation:

Although the use of cocaine in the medical field has reduced it was used as a  local numbing agent for oral and nasal procedures.

It is now mostly used for nasal surgery. The side effects of cocaine which are increase in the toxicity of cardiovascular system, glaucoma, and pupil dilation are not suitable for medical procedures. Sometimes cocaine is used for nasal cauterization.

sir frederic attributed inaccuracies to schemas. memory reconstruction is one part actual events and one part personal schema, which can result in inaccuracies when memories are reconstructed.