Lipitor, also known as atorvastatin, is a medication used to lower cholesterol levels in the blood. According to the sources provided, there is no specific mention of when adverse reactions with Lipitor were first noticed. However, the sources do provide information on potential side effects associated with the medication.

According to Drug Patent Watch [1], the FDA approved Lipitor in 1996. The National Center for Biotechnology Information (NCBI) [2] notes that while statins like Lipitor are generally well-tolerated, they can cause side effects such as muscle pain, liver damage, and an increased risk of diabetes. Medical News Today [3] also lists potential side effects of Lipitor, including headache, nausea, diarrhea, and joint pain.

It is important to note that not everyone who takes Lipitor will experience side effects, and the benefits of the medication in reducing the risk of heart disease may outweigh the potential risks for some individuals. However, anyone taking Lipitor or any other medication should be aware of potential side effects and discuss any concerns with their healthcare provider.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.ncbi.nlm.nih.gov/books/NBK430779/
[3] https://www.medicalnewstoday.com/articles/drugs-lipitor-side-effects