Lipitor is a medication that is used to lower cholesterol levels in the blood [2]. It works by inhibiting an enzyme in the liver that is responsible for producing cholesterol [2]. Lipitor does not have any direct effect on allergy medicine [2]. However, it is important to note that grapefruit juice can interact with Lipitor and increase the risk of side effects [3]. Grapefruit juice contains compounds that can inhibit the same enzyme that Lipitor inhibits, which can lead to increased levels of the medication in the bloodstream [3]. This can increase the risk of side effects such as muscle pain and liver damage [3]. Therefore, it is recommended to avoid consuming grapefruit juice while taking Lipitor [3].

Sources:
[2] https://www.webmd.com/drugs/2/drug-3330/lipitor-oral/details
[3] https://www.fda.gov/consumers/consumer-updates/grapefruit-juice-and-some-drugs-dont-mix