This is a must for the thyroid specialist and necessary knowledge for the thyroid patient. The thyroid gland can have a variety of inflammatory conditions, which are pathological states in which the thyroid gland is destroyed. The evolution is complex and can be “hyperthyroidism” – hypothyroidism – normal, etc. Misdiagnosis is not uncommon. The most common form is chronic lymphocytic thyroiditis, also known as Hashimoto’s disease, which is caused by the destruction of the thyroid gland by the body’s own toxic substances, namely autoantibodies, and can eventually lead to hypothyroidism. Hashimoto’s disease has a significant genetic predisposition and screening of the patient’s next of kin is necessary. Subacute thyroiditis is a type of thyroiditis between acute and chronic, characterized by pain in the thyroid area with lump formation, and can be moderately to highly febrile, evident in the late afternoon or evening. The disease is often preceded by a cold and can be easily misdiagnosed as pharyngitis or even a tumor, and requires special tests to confirm the diagnosis. Painless thyroiditis is an inflammatory thyroid condition that is not uncommon but often not properly diagnosed by physicians and is often misdiagnosed as common hyperthyroidism and treated with anti-thyroid medication. When pregnant or breastfeeding after delivery, the diagnosis requires a careful physical examination combined with thyrotropin receptor antibody TRAb and thyroid ultrasound, due to the limitations of the tests. This disease can also be seen in the postpartum period, when it is called postpartum thyroiditis. Blood tests can show either hyperthyroidism or hypothyroidism. Painless thyroiditis is self-limiting and most people recover spontaneously, but the hyperthyroid phase requires rest and symptomatic management. Acute suppurative thyroiditis is a rare or uncommon inflammation of the thyroid gland, mainly in children, due to abnormal development of the thyroid gland or other abnormalities of the neck, followed by a bacterial infection, such as abnormal development of the cheek cleft. It may have an acute onset with high fever and blood work consistent with septic inflammatory changes, but nail function is generally normal. Local manifestations include a painful mass on palpation of one side of the thyroid gland, which has a congested and red skin appearance with intense pressure pain and high tension. The disease requires prompt antimicrobial and surgical management. Radiation thyroiditis is an aseptic thyroiditis that occurs under specific circumstances, i.e. when hyperthyroidism or thyroid cancer iodine 131 treatment is followed by pain and edema in the thyroid area, even spreading to the throat leading to hoarseness and temporary loss of voice, which often occurs on the 2nd-5th day after treatment and requires glucocorticoid therapy in severe cases.