Lipitor is a brand name for atorvastatin, which is a medication used to lower cholesterol levels in the blood. According to the sources provided, there is no direct evidence to suggest that Lipitor affects antihistamines. However, it is important to note that Lipitor can interact with other medications, which may indirectly affect the effectiveness of antihistamines.

According to the NHS [3], Lipitor may interact with certain medications, including antifungal medications, antibiotics, and some HIV medications. These interactions can increase the risk of side effects, such as muscle pain and weakness. Therefore, it is important to inform your doctor or pharmacist if you are taking any other medications before starting Lipitor.

Erectile dysfunction is a potential side effect of Lipitor [2]. However, there is no evidence to suggest that this side effect is related to the use of antihistamines. Erectile dysfunction can be caused by a variety of factors, including age, underlying health conditions, and certain medications. If you are experiencing erectile dysfunction while taking Lipitor, it is important to talk to your doctor to determine the cause and explore potential treatment options.

In conclusion, there is no direct evidence to suggest that Lipitor affects antihistamines. However, Lipitor can interact with other medications, which may indirectly affect the effectiveness of antihistamines. It is important to inform your doctor or pharmacist of all medications you are taking before starting Lipitor to avoid potential interactions.

Sources:
[2] https://www.goodrx.com/conditions/erectile-dysfunction/can-medications-cause-erectile-dysfunction
[3] https://www.nhs.uk/medicines/atorvastatin/taking-atorvastatin-with-other-medicines-and-herbal-supplements/
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR