Based on the information available, it is important for individuals taking Lipitor, a medication used to treat high cholesterol, to be aware of potential herb-drug interactions.

According to Drugs.com, a leading drug information resource, St. John's Wort should be avoided while taking Lipitor [1]. This herb can decrease the effectiveness of Lipitor by increasing the activity of certain liver enzymes that break down the medication [1].

Another resource, DrugPatentWatch.com, states that garlic and red yeast rice are two herbs that can also interact with Lipitor [2]. Garlic can increase the risk of bleeding when taken with Lipitor, while red yeast rice contains a natural form of a statin, the class of drug that Lipitor belongs to [2]. This can increase the risk of side effects associated with statins [2].

In summary, St. John's Wort, garlic, and red yeast rice are herbs that should be avoided while taking Lipitor due to potential herb-drug interactions. It is always recommended to consult with a healthcare provider before starting any new herbal supplements while on medication.

Sources:
[1] <https://www.drugs.com/drug-interactions/lovastatin-with-st-john-s-wort-13,473.html>
[2] <https://www.drugpatentwatch.com/drugs/lovastatin/interactions>