Hi, N-acetylcysteine (NAC) is a supplement that has been shown to have various health benefits, including antioxidant properties and mucolytic effects. However, it is important to consider potential interactions with other medications before taking any supplement. In general, NAC is considered safe for most people when taken at recommended doses. However, there are some known interactions with certain medications, including nitroglycerin, nitroprusside, and activated charcoal. In addition, there is some evidence that NAC may interfere with the effectiveness of certain chemotherapy drugs, so it is important to discuss the use of NAC with your doctor if you are undergoing cancer treatment. As for the medications you are currently taking, there are no known interactions between NAC and levothyroxine, tamsulosin hydrochloride, hydrochlorothiazide, or rabeprazole. However, there is a theoretical possibility that NAC may interact with finasteride, as both substances are metabolized by the liver. Therefore, it is important to talk to your doctor before adding NAC to your regimen if you are taking finasteride. Overall, while NAC may have potential benefits, it is always important to talk to your doctor before starting any new supplement, especially if you are taking multiple medications. Your doctor can advise you on potential interactions and whether NAC is safe for you to take based on your health situation. If you require a personalized response, kindly use the Ask A Doctor service and post a follow-up. Take care. Hope I have answered your question. Regards, Dr. Priyanka, General & Family Physician