Serum Sickness: Causes, Symptoms & Treatment

Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson goes over a condition called serum sickness. You'll learn what can cause it, what happens in the body as a result of it, what signs and symptoms might occur, and how it can be managed.

Serum Sickness

When you get attacked by the flu virus, your immune system's fight against that virus is partially responsible for all those signs and symptoms you feel, like coughing, sneezing, and so on. But the body's immune system doesn't react solely to viruses, bacteria, and fungi. It can simply react to foreign proteins in general, such as those found in serum. Serum is the portion of blood that remains once the proteins and cells involved in clotting blood have been removed.

Your body's reaction to foreign serum might cause you to get really ill as per serum sickness, a type III hypersensitivity reaction. Let's go over this condition's causes, symptoms, and treatment options.


A type III hypersensitivity reaction is also known as an immune complex hypersensitivity. This type of allergy-like reaction namely involves two components: antibodies and antigens. Antibodies are proteins that attach to foreign substances, antigens, in order to inactive them, destroy them, or serve as a beacon for immune system cells to come and destroy them instead.

In a type III hypersensitivity reaction, intermediate sized immune complexes are formed. An immune complex is like a chain or clump of a bunch of antibodies attached to numerous antigens. Normally, this clump is destroyed by white blood cells. But in this hypersensitivity reaction, the clumps are too small to trigger a normal response from immune system cells to come and destroy them. This allows the clumps to get stuck in a person's joints, blood vessels, and kidneys (among other places) and wreak havoc by triggering inflammation wherever they get stuck.

If a person is injected with a medication containing a foreign protein, serum sickness may be the end result. For example, a person might be exposed to a toxin and given something called antiserum as a treatment. This is another animal's serum that contains a lot of antibodies designed to neutralize a toxin or poison of some sort. Other medications that can lead to serum sickness or serum-sickness like signs and symptoms include:

  • Hormones
  • Vaccines
  • Penicillins and other antibiotics

Signs & Symptoms

The signs and symptoms of serum sickness most commonly develop 1-3 weeks after exposure to the offending agent. Signs and symptoms of this disorder, from most to least common, include:

  • Fever
  • Malaise
  • Rash or hives
  • Joint pain
  • Gastrointestinal issues such as pain, nausea, vomiting, or diarrhea
  • Headaches
  • Muscle pain
  • Blurry vision
  • Difficulty breathing
  • Enlarged lymph nodes


The most important treatment, if you will, of serum sickness is removing the offending substance. Next, management is aimed at addressing the person's individual issues. For example:

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