Small Bump Behind Ear That Comes and Goes

Quick Answer

A small, moveable bump behind the ear that comes and goes is most commonly a swollen lymph node responding to a minor infection (cold, ear infection, scalp irritation), a sebaceous cyst that fluctuates in size, or a lipoma (benign fatty lump). These are almost always harmless. However, a bump that is hard, fixed in place, growing steadily, or accompanied by unexplained weight loss, night sweats, or persistent fatigue should be evaluated by a doctor.

The Most Common Causes

Swollen Lymph Node

This is the most likely explanation for a bump that comes and goes. You have a cluster of lymph nodes behind each ear (posterior auricular lymph nodes) that are part of your immune system. When your body fights an infection — even a mild one — nearby lymph nodes swell as they produce immune cells and filter bacteria or viruses.

A swollen lymph node behind the ear is often triggered by:

A cold or upper respiratory infection
An ear infection (otitis media or externa)
A skin infection or irritation on the scalp, including dandruff or folliculitis
A dental infection on the same side
Insect bites on the head or neck

The node swells to pea-sized or sometimes marble-sized, feels rubbery and moveable under the skin, and may be slightly tender. Once the infection resolves, the lymph node shrinks back to its normal size over days to weeks. This is why the bump seems to "come and go" — it appears during infections and recedes between them.

Sebaceous Cyst

A sebaceous (epidermal inclusion) cyst is a closed sac under the skin filled with keratin, a thick, white or yellowish protein material. These cysts form when a hair follicle or oil gland duct becomes blocked. The area behind the ear has many sebaceous glands, making it a common location for these cysts.

Sebaceous cysts tend to:

Feel round, smooth, and firm
Move freely under the skin when you press on them
Grow slowly over weeks to months
Sometimes shrink or feel less noticeable, then enlarge again (explaining the "comes and goes" quality)
Occasionally become inflamed, red, and tender if the cyst wall ruptures under the skin or gets infected

They are entirely benign but do not resolve on their own permanently. A dermatologist can remove them with a simple outpatient procedure if they are bothersome.

Lipoma

A lipoma is a benign growth of fat cells just beneath the skin. They feel soft, doughy, and moveable — almost like a small rubber ball under the skin. Lipomas grow very slowly and are usually painless. They do not come and go in the true sense, but their apparent size can fluctuate with weight changes, water retention, and how you happen to notice them.

Mastoiditis (Less Common)

The mastoid bone directly behind your ear contains air cells that can become infected, usually as a complication of untreated middle ear infections. Mastoiditis causes tenderness, redness, and swelling over the bone itself (not a discrete moveable bump). It is accompanied by ear pain, fever, and sometimes drainage from the ear. This is uncommon in adults but requires medical treatment when it occurs.

Acne or Folliculitis

A pimple or inflamed hair follicle behind the ear can feel like a sudden bump. These are typically red, tender, and come to a head within days. The skin behind the ear has oil glands and hair follicles that can become clogged just like anywhere else on the body.

Warning

When to See a Doctor

While most bumps behind the ear are benign, schedule an appointment if you notice:

A bump that is hard and does not move when you press on it — fixed lumps can indicate something other than a cyst or lymph node
Steady growth over weeks without any sign of shrinking
Size larger than 2 centimeters (about the size of a grape)
Associated symptoms like unexplained weight loss, night sweats, persistent fatigue, or fevers without an obvious infection
Multiple swollen lymph nodes in different parts of the body (neck, armpits, groin) simultaneously
Skin changes over the bump — redness, ulceration, or tethering of the skin
A lump that has persisted unchanged for more than four to six weeks without an identifiable cause
Hearing loss or persistent ear drainage on the same side

What to Do When You Find a Bump

Do not panic. The overwhelming probability is that it is a swollen lymph node or a cyst. Both are benign and common.

Track it. Note the size, how it feels, and whether it is tender. Check it again in two to three weeks. A lymph node that was fighting an infection should be noticeably smaller by then.

Do not squeeze or try to pop it. If it is a cyst, squeezing can rupture the cyst wall under the skin, causing inflammation and potential infection. If it is a lymph node, compressing it serves no purpose.

Consider recent illnesses or skin issues. Did you have a cold recently? An earache? A pimple or cut on the scalp? Dandruff flare-up? Any of these can cause the lymph node behind the ear to swell.

Warm compress. A warm, damp cloth held against the bump for 10 to 15 minutes, three to four times a day, can help a swollen lymph node drain more efficiently and can bring an inflamed cyst to resolution faster.

See a doctor if it persists. If the bump is still there and unchanged after four to six weeks, or if it is growing, a doctor can examine it and may order an ultrasound to characterize it. Ultrasound is painless and very good at distinguishing between a cyst, lymph node, lipoma, and other soft tissue lumps.