When taking Synthroid for hypothyroidism, it is recommended to avoid certain foods or medications that can affect its absorption. These include mineral supplements like iron or calcium, multivitamins, and antacids. It is best to not take these within 4 hours of taking Synthroid. Additionally, dairy products or foods high in calcium can also interact with Synthroid, so it is important to be consistent in your diet when taking the medication. Taking Synthroid on an empty stomach about 30 minutes before a meal is a good way to minimize any interactions. Your doctor will likely perform blood tests to monitor the effectiveness of the medication and make any necessary dosage adjustments.