Actinomycosis is a rare bacterial infection. It causes pus to collect in the body. It may start in the:

  • Jaw
  • Lungs
  • Abdomen
  • Uterus

Rarely, the infection can spread from one place in the body to another.

Abdominal Abscess
Abdominal Abscess

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Certain bacteria cause actinomycosis. They are normal in the mouth and sometimes in the bowels. They get into the body through breaks in the tissues. Tooth decay causes infections in the mouth and jaw. This is the most common type.

Risk Factors

This infection is more common in men. Other things that raise the risk are:

  • Problems with teeth and gums
  • Lung problems
  • Bowel surgery
  • Problems with an intrauterine device (IUD)
  • Diabetes
  • Weak immune system


Symptoms depend on the where the infection starts. They may involve:

  • Swelling in the mouth, neck, or jaw
  • Pus with tiny, yellowish specks
  • Pus that drains through the skin
  • Fever
  • Weight loss
  • Cough
  • Swelling or a hard lump in the belly


The doctor will ask about your symptoms and health history. A physical exam will be done. Other tests may include:

  • Testing of fluids, pus, or phlegm
  • A biopsy—to look at the tissues


The infection is treated with antibiotics. The infection site will be drained. Surgery may be done to remove some pieces of tissue and bone.

It is common for the infection to come back, even after getting care.


Good dental care may lower the risk of infection in the jaw.


Family Doctor—American Academy of Family Physicians

Mouth Healthy—American Dental Association


Canadian Dental Association

Health Canada


Actinomycosis. Merck Manual Professional Version website. Available at: Accessed February 4, 2021.

Cervicofacial actinomycosis. EBSCO DynaMed website. Available at: Accessed February 4, 2021.

Moturi K, Kaila V. Cervicofacial actinomycosis and its management. Ann Maxillofac Surg. 2018;8(2):361-364.

Last reviewed September 2020 by David L. Horn, MD, FACP  Last Updated: 2/4/2021