Hi, thank you for your query at Helathcare Magic... Yes, in some cases, hair loss is one of the Levothyroxine s side effects. Actually, not all the patients experience this. However, advanced age can be one factor that aggravate the adverse effects. Hair loss is generally a part of the body s natural reaction that does not endanger health. Losing 100 strands of hair per day is still considered normal, but if excessive it would be a problem. There are several medical conditions that cause hair loss for example: 1. High DHT hormone (dihydrotestoteron) -The hair becomes thinner and quickly fall off the roots -Often in men causing androgenetic alopecia. 2. Nutrition is not good 3. Effect of drugs including chemotherapy Things you can do at home: -Do not wash too often, preferably 2 days or once a day (if necessary) -Use shampoo containing ginseng, panthenol, and other ingredients that can strengthen the roots of hair and avoid massage too hard when shampooing - Do not pull, twist, and tie the hair too strong - Do not comb your hair when the hair is wet - Use a toothed comb that rarely and comb from the bottom first - Reduce hair care with chemicals and electronic products - Live a healthy lifestyle by eating healthy foods, adequate rest, and regular exercise - Manage stress well If the hair loss reaches an alarming level, I recommend that you consult with your treating doctor or a dermatologist to determine the exact cause and appropriate therapy. Thank you and take care.