Thyroiditis is an inflammation of the thyroid gland, a gland in the neck which is a critical part of the endocrine system. When the thyroid becomes inflamed, it is unable to perform its normal functions, typically producing less hormones than it normally would, causing a variety of health problems. There are a number of different types and causes of thyroiditis, some of which require treatment, and some of which will resolve on their own. Medical attention is important to uncover the cause of the thyroiditis, and to confirm that there are no lumps or other irregularities present in the thyroid.

Any time an “-itis” is involved, it's a clue that the condition is characterized by inflammation, often an inflammation caused by infection. There are four main types of thyroiditis: Hashimoto's thyroiditis, subacute thyroiditis, silent thyroiditis, and acute thyroiditis. Each requires a different treatment approach, which is why it's important to consult a doctor when symptoms like a painfully swollen neck, fatigue, muscle weakness, pale skin, and fever appear, so that the condition and cause can be diagnosed.

Hashimoto's thyroiditis is an autoimmune disorder which causes inflammation of the thyroid when the immune system starts attacking the thyroid gland. It requires treatment with supplemental thyroid medication to make up for the hormones the body is not producing. Usually, the symptoms clear up after the patient starts using the medication, although the medication needs to be taken for life to prevent a recurrence of symptoms.

Subacute thyroiditis, also known as De Quervain's or viral thyroiditis, is caused by an infection. Viral infections in the neighborhood of the thyroid, such as upper respiratory infections, can lead to subacute thyroiditis. Usually, the patient is encouraged to rest and take aspirin to reduce the inflammation and the swelling until the pain in the neck goes down after a few weeks. Acute thyroiditis, on the other hand, is caused by a bacterial infection of the thyroid itself, leading to rapid swelling, pain, and heat around the thyroid gland. It requires immediate surgical intervention to drain the thyroid, and thyroid medications may need to be taken if the gland was damaged.

Silent thyroiditis is a very rare form of thyroid inflammation which manifests in some women after pregnancy and birth. The thyroid swells slightly and becomes hard to the touch, developing within a year of the birth, but it usually clears up within a few months. This type of thyroiditis is also called postpartum thyroiditis.