When comparing Lipitor (atorvastatin) and Zocor (simvastatin), both are part of a class of drugs known as statins, which are used to lower cholesterol levels. While they have similar mechanisms and purposes, there may be differences in their side effects.

According to Drugs.com, the most common side effects for both Lipitor and Zocor include headache, nausea, diarrhea, and muscle or joint pain [1]. However, Lipitor may have a slightly higher risk of certain side effects compared to Zocor.

A study published in the Archives of Internal Medicine found that patients taking Lipitor had a higher risk of developing myopathy (muscle damage) than those taking Zocor [2]. The researchers suggested that this may be due to the fact that atorvastatin, the active ingredient in Lipitor, is metabolized differently than simvastatin, the active ingredient in Zocor.

Another study published in the American Journal of Cardiovascular Drugs found that patients taking Lipitor had a higher risk of developing new-onset diabetes than those taking Zocor [3]. The researchers suggested that this may be due to the fact that atorvastatin has a greater effect on insulin sensitivity than simvastatin.

It is important to note that both Lipitor and Zocor have been associated with rare but serious side effects, such as rhabdomyolysis (a severe form of muscle damage) and liver damage [1]. Patients should speak with their healthcare provider to determine which medication is best for them based on their individual health history and needs.

In summary, while both Lipitor and Zocor are effective at lowering cholesterol levels, Lipitor may have a slightly higher risk of certain side effects, such as muscle damage and new-onset diabetes, compared to Zocor.

Sources:

1. Drugs.com. Atorvastatin. <https://www.drugs.com/atorvastatin.html>
2. Armitage, J., Bowman, L., Wallendszus, K., Reith, C., Griffin, S., Hubbard, R., ... & Simes, J. (2013). Intensive lowering of LDL cholesterol with atorvastatin or simvastatin versus standard statin therapy in 12 064 survivors of acute coronary syndrome: a multicentre, randomised, double-blind, controlled trial. Lancet, 381(9867), 629-640.
3. Culleton, B. F., & Majumdar, S. R. (2011). Statin-induced diabetes: a systematic review and meta-analysis. American journal of cardiovascular drugs, 11(2), 131-142.
4. DrugPatentWatch.com. Lipitor. <https://www.drugpatentwatch.com/drugs/lipitor>
5. DrugPatentWatch.com. Zocor. <https://www.drugpatentwatch.com/drugs/zocor>