Based on the available information, it is possible for Lipitor and fish oil to cause negative reactions when used together. According to a study published by NPR [1], statins, such as Lipitor, have been found to be vastly superior to supplements like fish oil in reducing cholesterol levels. The study suggests that taking both Lipitor and fish oil may not provide additional benefits and could potentially lead to adverse effects.

It is important to note that Lipitor, a medication used to treat high cholesterol, can have side effects on its own. According to Drug Patent Watch [2], common side effects of Lipitor include muscle pain, liver damage, and increased blood sugar levels.

Fish oil, on the other hand, is a dietary supplement that is generally considered safe when taken in recommended doses. However, Medical News Today [3] states that fish oil can cause side effects such as bloating, gas, and diarrhea.

When taken together, Lipitor and fish oil may interact and cause negative reactions. For example, both Lipitor and fish oil can affect blood clotting, which could increase the risk of bleeding. Additionally, taking both medications together could increase the risk of muscle damage, a side effect of Lipitor.

It is always recommended to consult with a healthcare provider before starting any new medication or supplement, especially if taking other medications. A healthcare provider can provide personalized advice based on an individual's medical history and current medications.

In summary, based on the available information, it is possible for Lipitor and fish oil to cause negative reactions when taken together. It is important to consult with a healthcare provider before starting any new medication or supplement.

Sources:
[1] <https://www.npr.org/sections/health-shots/2022/11/06/1134094540/statins-vs-supplements-new-study-finds-one-is-vastly-superior-to-cut-cholesterol>
[2] <https://www.drugpatentwatch.com/p/tradename/LIPITOR>
[3] <https://www.medicalnewstoday.com/articles/fish-oil-vs-statins>