Hi, Armour Thyroid is a natural desiccated thyroid extract that is used in the treatment of underactive thyroid or hypothyroidism. But like other medications this product has some side effects of its own. Side effects of this medication are feeling unwell or nausea, vomiting, stomach problems, anxiety, changes in appetite, chest pain, diarrhea, headache, fever, fast or irregular heartbeat, changes in menstrual cycles, mood changes, sweating, shakiness, dizziness, allergic reactions and many more. Despite experiencing side effects, you must not stop this medication without consulting your doctor. In case of any side effect, you should inform your doctor at the earliest for medical help. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Zubayer Alam, General And Family Physician