Forehead swelling can occur as a result of a wide variety of conditions. It is usually a symptom of another underlying problem and is not generally considered serious or life-threatening. Some of the common causes of forehead swelling include skin problems, but the swelling can also be a sign of an internal condition affecting the head.

One of the most common causes of forehead swelling is contact dermatitis, an allergic reaction that occurs when the skin touches a substance that it finds irritating. Irritants that can aggravate the skin and lead to contact dermatitis can include cosmetics, fragrances, metals, or fabrics. If one of these irritants comes into contact with the forehead, such as from cosmetics or the fabric lining of a hat, it can cause the area to become red, itchy, and swollen. Contact dermatitis can usually be treated with the use of topical corticosteroid medications, which relieve the symptoms of the reaction.

Another skin condition that can contribute to forehead swelling is sunburn. Overexposure to the sun can lead to severe sunburn that can actually cause blisters, as well as slight swelling of the affected area. The skin has to regenerate new cells to heal burns, but certain treatments can be used to relieve pain, including applying cold compresses or aloe vera gel for sunburn.

Forehead swelling can also be caused by a skin condition known as sebaceous cysts. A sebaceous cyst is a small growth that develops when the oil glands in the skin produce excessive amounts of oil. The oil can accumulate under the skin and form a cyst. The forehead is one of the skin areas that tends to be more prone to excess oil; therefore, it is one of the most common places on the skin for these cysts to form. Sebaceous cysts can form under the surface of the skin on the forehead and cause pain and swelling in the area.

Although most cases of forehead swelling are due to skin conditions, swelling can also be caused by a physical injury to the forehead. If a person experiences trauma to the forehead, fluids can collect in the area and cause swelling. In general, applying a cold compress to the forehead is recommended as sufficient treatment to reduce swelling; however, if a person who has experienced trauma to the forehead also has other symptoms such as dizziness, nausea, fever, or disorientation, it could be a sign of a concussion or other serious head injury, and care will usually be