Demodex Mites in Humans

Updated March 23, 2017

Demodex refers to a condition in warm-blooded animals that is caused by a mite known as the demodectic mange mite. The mite responsible for causing demodex lives in the hair follicles of every warm-blooded animal in the world, including humans, and manifests when the immune system is suppressed. Demodex can be found in every part of the world, in every climate where mammals are found.


Demodex mites are among the smallest arthropods known to man. The adults measure around .3mm to .4mm in length and have a segmented, elongated body shape. The demodex mite is covered with anchoring scales that keep it firmly affixed to its host's hair shafts and survives by eating skin cells and oils that accumulate in the follicles. These bugs are photosensitive, and even though they have the ability to leave the hair follicle, they generally don't until nighttime.

What Causes an Infection

Active demodex infections will generally manifest as itchy, red, irritated skin. The follicles will enlarge due to the irritation and become infected. It is at this point that the hair will begin to fall out. As a reaction to the irritation, the skin will produce more sebum, the oil that lubricates the skin, which in turn will stimulate the reproduction of the demodex mites. Demodex can reproduce and mature in a very short amount of time, usually in two weeks or less, creating an infestation very quickly.


Noticeable symptoms of demodex infection are frequent redness, hair loss, bumps, and itching of particular areas of the skin, especially around the hair follicles. Many skin conditions can be traced back to active demodex infections such as Acne Rosacea.


Diagnosis of demodex in humans is accomplished by taking several scrapings of the skin and viewing under a microscope. The mites themselves can be seen on the slide, when it is determined whether they are alive and active or not. If there are live mites, treatment will ensue, until two subsequent scrapings reveal no mites, or no live mites.


Treatment options consist of several topical insecticides and a few systemic drugs. Depending on the severity of the infection, treatment may not be indicated all, while in more severe cases, topical applications of metronidazole and the oral use of antibiotics to prevent secondary bacterial infections is usually indicated.

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