Chemosis is swelling of the tissue that lines the eyelids and surface of the eye (conjunctiva).

Fluid-filled conjunctiva; Swollen eye or conjunctiva

In general, chemosis is a nonspecific sign of eye irritation. The outer surface covering appears to have fluid in it. Often, the eye area swells so much that you can't close your eyes properly.

Chemosis is often related to an allergic response or infection.

• Angioedema
• Allergic response
• Viral infection (conjunctivitis)

Over-the-counter antihistamines and cool clothes placed on the eyes may help relieve symptoms due to angioedema or allergies.

If symptoms continue, see your doctor.

Call your doctor if your symptoms do not go away. Also call if you have other symptoms such as eye pain, change in vision, difficulty breathing, or fainting.

The doctor will perform a physical exam and ask questions about your symptoms, which may include:

• When did it start?
• How long does the swelling last?
• How bad is the swelling?
• How much is the eye swollen?
• What, if anything, makes it better or worse?
• What other symptoms do you have? (For example, breathing problems)

Your doctor may prescribe an eye cream to reduce swelling. If the swelling is caused by an infection, antibiotics will be given.

Angioedema is a swelling, similar to hives, but the swelling is beneath the skin rather than on the surface. Hives are often called welts. They are a surface swelling. It is also possible to have angioedema without hives.

See also: Hereditary angioedema

Angioneurotic edema; Welts

Angioedema may be caused by an allergic reaction. During the reaction, histamine and other chemicals are released into the bloodstream. The body releases histamine when the immune system detects a foreign substance called an allergen.

In many cases, the cause of angioedema is never found.

The following may cause angioedema:

• Animal dander (scales of shed skin)
• Exposure to water, sunlight, cold or heat
• Foods (such as berries, shellfish, fish, nuts, eggs, milk, and others)
• Insect bites
• Medications (drug allergy), such as antibiotics (penicillin and sulfa drugs), nonsteroidal anti-inflammatory drugs (NSAIDs), and blood pressure medicines (ACE inhibitors)
• Pollen

Hives and angioedema may also occur after infections or with other illnesses (including autoimmune disorders such as lupus, and leukemia and lymphoma).

A form of angioedema runs in families and has different triggers, complications, and treatments. This is called hereditary angioedema, and it is not discussed in this article.

The main symptom is sudden swelling below the skin surface. You may also develop welts or swelling on the surface of your skin.

The swelling usually occurs around the eyes and lips. It may also be found on the hands, feet, and throat. The swelling may form a line or be more spread out.

The welts are painful and may be itchy. They turn pale and swell if irritated. The deeper swelling of angioedema may also be painful.

Other symptoms may include:

• Abdominal cramping
• Breathing difficulty
• Swollen eyes and mouth
• Swollen lining of the eyes (chemosis)

The doctor will look at your skin and ask you if you have been exposed to any irritating substances. A physical exam might reveal abnormal sounds (stridor) when you breathe in if the throat is affected.

Rarely, the health care provider may perform blood tests or allergy testing.

Mild symptoms may not need treatment. Moderate to severe symptoms may need treatment. Breathing difficulty is an emergency condition.

Cool compresses or soaks can provide pain relief.

Medications used to treat angioedema include:

• Antihistamines
• Anti-inflammatory medicines (corticosteroids)
• Epinephrine
• Ranitidine (Zantac)
• Terbutaline (a bronchodilator)

If the person has trouble breathing, seek immediate medical help.

See: Breathing difficulties - first aid

At the hospital, a tube may be placed in the throat to keep the airway open.

Angioedema that does not affect the breathing may be uncomfortable, but is usually harmless and goes away in a few days.

• Anaphylactic reaction
• Life-threatening airway blockage (if swelling occurs in the throat)

Call your health care provider if:

• Angioedema does not respond to treatment
• It is severe
• You have never had angioedema before

Go to the emergency room or call the local emergency number (such as 911) if you have:

• Abnormal breathing sounds (stridor)
• Difficulty breathing
• Fainting
• Wheezing

To prevent angioedema from coming back:

• Avoid irritating the affected area.
• Stay away from known allergens.

Never take medications that are not prescribed for you.

Dreskin SC. Urticaria and angioedema. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 273.

Temino VM, Peebles RS Jr. The spectrum and treatment of angioedema. Am J Med. 2008;121:282-286.

Wasserman SI. Approach to the person with allergic or immunologic disease. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 270.