The mastoid bone is located behind the ear. Mastoiditis is swelling or infection of this bone. Over time, this can cause the bone tissue to break down.


The mastoid bone is like a sinus and has many small air pockets in its structure. It connects to the middle ear.

Mastoiditis is most often caused by a bacterial infection that has entered these air spaces.

These bacteria often come from a long lasting middle ear infection .

The Middle Ear
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Risk Factors

Mastoiditis is more common in young children. It rarely occurs in adults. Factors that may increase your risk of mastoiditis include:

  • A recent middle ear infection that was not treated with antibiotics
  • A weak immune system
  • Abnormal skin growth in the middle ear known as cholesteatoma


Mastoiditis may cause:

  • Fever
  • Irritability
  • Tiredness
  • Swelling behind the ear, pushing it forward
  • Ear pain
  • Discharge from the ear
  • Decreased hearing


You will be asked about your symptoms and medical history. A physical exam will be done. Your doctor may suspect mastoiditis based on your recent history of an ear infection and the physical exam.

A CT scan may be done to look for fluid around the mastoid.

Any fluid discharge from your ear may also be tested to look for the specific cause of the infection.


Treatment options include:


Antibiotics will be given to help fight the bacterial infection. This is usually done by IV followed by medications taken by mouth.

Over-the-counter medications may also be advised to relieve pain and swelling.


Surgery may be needed to treat mastoiditis that does not respond to medication. This can be done with:

  • Myringotomy and tympanostomy —surgery to drain fluid and place tubes in the ear to keep the middle ear open to prevent fluid build-up
  • Mastoidectomy—removal of the mastoid bone if the infection is severe and does not respond to other treatments


Mastoiditis is most often caused by an untreated or lasting middle ear infection. If you suspect you have an ear infection, see your doctor. Follow your doctor’s treatment advice.

Revision Information

  • Reviewer: EBSCO Medical Review Board James Cornell, MD
  • Review Date: 09/2018 -
  • Update Date: 09/03/2015 -