Lipitor, also known as atorvastatin, is a prescription medication used to lower cholesterol levels in the blood. According to MedlinePlus [3], Lipitor belongs to a group of medications called statins, which work by blocking an enzyme that the liver uses to make cholesterol. While Lipitor is generally safe and well-tolerated, it can cause some side effects, including muscle pain, weakness, and tenderness, as well as liver problems.

As for herb interactions, there is limited information available on the potential interactions between Lipitor and herbs. However, a study published in the Journal of Pharmacy and Pharmacology [2] suggests that some herbs, including St. John's Wort, may interact with statins, including Lipitor. St. John's Wort is a popular herbal supplement used to treat depression, anxiety, and other conditions. The study found that St. John's Wort may reduce the effectiveness of statins, which could lead to higher cholesterol levels and an increased risk of heart disease.

Another study published in the Journal of the American College of Cardiology [1] suggests that grapefruit juice may also interact with Lipitor. Grapefruit juice contains compounds that can interfere with the metabolism of certain medications, including Lipitor. This can lead to higher levels of the drug in the bloodstream, which can increase the risk of side effects.

In summary, while Lipitor is generally safe and well-tolerated, it can cause some side effects, including muscle pain, weakness, and tenderness, as well as liver problems. Limited information is available on the potential interactions between Lipitor and herbs, but some studies suggest that St. John's Wort and grapefruit juice may interact with the drug. If you are taking Lipitor and are considering taking an herbal supplement or drinking grapefruit juice, it is important to talk to your doctor first to determine if there are any potential risks or interactions.

Sources:
1. Journal of the American College of Cardiology: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5562283/
2. Journal of Pharmacy and Pharmacology: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4593660/
3. MedlinePlus: https://medlineplus.gov/druginfo/meds/a600045.html