Lipitor is a brand name for atorvastatin, which is a medication used to lower cholesterol levels in the blood [1]. Benadryl is a brand name for diphenhydramine, which is an antihistamine used to relieve symptoms of allergies, hay fever, and the common cold [2].

There is no direct evidence that suggests Lipitor can affect the effectiveness of antihistamines like Benadryl. However, a study published in the Journal of Allergy and Clinical Immunology found that statins, a class of drugs that includes Lipitor, can reduce the severity of allergic reactions in some individuals [3].

While this study suggests that statins may have some effect on allergic reactions, it is important to note that it does not specifically address the interaction between statins and antihistamines. It is also important to remember that every individual is different and may react differently to medications. Therefore, it is always best to consult with a healthcare provider before taking any new medications or changing your current medication regimen.

In conclusion, there is no direct evidence to suggest that Lipitor can affect the effectiveness of antihistamines like Benadryl. However, it is always best to consult with a healthcare provider before taking any new medications or changing your current medication regimen.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.webmd.com/drugs/2/drug-5680/benadryl-oral/details
[3] https://pubmed.ncbi.nlm.nih.gov/22947909/