7 Common Causes of a Lump on the Back of the Neck

Finding a lump on the back of your neck can be concerning, but many are harmless cysts, boils, or ingrown hairs that resolve on their own. However, if the lump persists or is accompanied by other symptoms, it’s important to seek medical advice to rule out conditions like swollen lymph nodes or other underlying issues.

1. Swollen Lymph Nodes

Swollen lymph nodes are small, bean-shaped glands in your neck that help your body fight infections. When swollen, they can feel like a lump on the neck, under the jaw, or behind the ears.

Causes: Lymph nodes can swell during an infection, like a cold, flu, or strep throat. Less often, they enlarge due to autoimmune issues, certain medications, or cancers like lymphoma.

Symptoms may include:

• Tenderness or soreness in the neck
• Fever, sore throat, or runny nose
• General fatigue or feeling unwell
• Nodes that feel firm or fixed in place (may signal a more serious cause)

Treatment: Swollen lymph nodes often shrink on their own once the infection clears. Rest, fluids, and over-the-counter pain relievers can ease discomfort.

2. Cysts

Cysts are small sacs under the skin and feel like a lump on the back of the neck. They are usually filled with fluid, keratin (a skin protein), or sebum (an oily substance from skin glands).

Causes: The most common type on the neck is an epidermoid cyst, which grows slowly and is usually harmless. These typically appear in hair-bearing areas and might have a small pore at the center.

Symptoms may include:

• A small lump just beneath the skin
• Pain or tenderness, especially if inflamed
• Redness or swelling around the cyst
• Drainage of foul-smelling fluid or thick material

Treatment: Epidermoid cysts often don’t need treatment and may go away on their own, though they can return if they drain naturally. If a cyst is bothersome, inflamed, or infected, treatment may include steroid injections, drainage, or surgical removal. Complete excision, which removes both the cyst and its wall, is the most effective way to prevent it from coming back.

3. Ingrown Hairs

Ingrown hairs happen when a hair grows back into the skin instead of rising to the surface. On the back of the neck, they can feel like a small lump and may look like a pimple or red bump.

Causes: Shaving, waxing, or friction from clothing can cause hairs to curl back or get trapped under the skin. People with curly or coarse hair are more likely to develop ingrown hairs.

Symptoms may include:

• Redness and inflammation of the skin
• Tender bumps that may fill with pus
• Itching or irritation around the hair follicle
• Possible scarring if the problem recurs or is untreated

Treatment: Ingrown hairs often heal on their own without treatment. For chronic or bothersome cases, strategies include letting the hair grow longer before shaving, avoiding shaving the area entirely, or trimming with clippers instead of a razor. Permanent hair removal methods, such as electrolysis and laser therapy, can help prevent ingrown hairs from coming back.

4. Boils

Skin boils are painful, pus-filled lumps that form when bacteria infect and inflame a hair follicle or oil gland. On the back of the neck, they may start as a tender red bump and grow larger over several days.

Causes: Boils are usually caused by Staphylococcus aureus bacteria entering the skin through a small cut, scrape, or irritated hair follicle. Friction from collars, helmets, or poor hygiene can increase the risk.

Symptoms may include:

• A swollen, red lump under the skin that may be tender to the touch
• Gradual growth over several days, sometimes reaching the size of a golf ball
• A white or yellow center that may ooze, weep, or crust
• Itching or irritation before the boil appears
• Fever, fatigue, or general discomfort if the infection spreads

Treatment: Most boils drain on their own within two weeks. Applying a warm compress can help speed up the process. Larger, infected, or more painful boils may need to be drained by a healthcare provider. Antibiotics may be prescribed if the infection is severe, spreads, or recurs often.

5. Lipomas

Lipomas are slow-growing, noncancerous fatty lumps that form just under the skin. They are usually soft, rubbery, and easy to move when pressed, and can appear as a lump on the back of the neck.

Causes: The exact cause isn’t clear, but genetics may play a role since lipomas often run in families. They develop when fat cells grow in a clump and form a benign (noncancerous) mass.

Symptoms may include:

• A small lump (about 0.5 to 1 inch) just under the skin
• Soft, rubbery consistency that moves easily when pressed
• Typically painless and slow-growing over years
• May become bothersome if located in a noticeable or uncomfortable area

Treatment: Lipomas usually don’t need treatment since they are harmless and painless. A healthcare provider may remove one if it becomes painful, infected, or bothersome. Most can be removed in your provider’s office using local anesthesia. Deeper lipomas may require surgery under general anesthesia.

6. Muscle Knots

Muscle knots (also called trigger points) are tight, sensitive areas of muscle that feel like small lumps under the skin. They are common on the back of the neck and can sometimes be mistaken for other types of lumps.

Causes: Poor posture, stress, overuse of muscles, or an acute injury can lead to muscle fibers tightening and forming knots. Spending long hours at a desk or sleeping in an awkward position are frequent triggers.

Symptoms may include:

• A firm or tender lump in the neck muscles
• Pain that worsens with movement or pressure
• Stiffness or reduced range of motion
• Headaches or shoulder pain that radiates from the knot

Treatment: Rest, stretching, and gentle massage can help relax the affected muscle. Applying heat or using over-the-counter pain relievers may reduce discomfort. Physical therapy, trigger point injections, or other medical treatments may be recommended if the muscle knot does not improve.

7. Nodular Acne

Nodular acne is a severe type of acne that causes large, firm, and painful lumps under the skin. On the back of the neck, these nodules can feel like deep, hard bumps that might take weeks or months to go away.

Causes: Nodular acne develops when hair follicles become clogged with oil, dead skin cells, and bacteria. Hormonal changes, genetics, and stress can increase the risk of developing this type of acne.

Symptoms may include:

• Large, hard, and painful lumps under the skin
• Redness and swelling in the affected area
• Scarring, if not properly treated
• Clusters of nodules in one area of the neck or back

Treatment: Over-the-counter acne treatments are usually not effective for nodular acne. A dermatologist may prescribe oral antibiotics, hormonal therapy, or isotretinoin (a strong acne medication). Treating nodular acne early helps prevent scarring and long-term skin damage.

When to See a Healthcare Provider

Contact your healthcare provider if you have any of the following symptoms:

• A lump that doesn’t go away or improve after two to three weeks
• A lump that increases in size or has an irregular shape
• A lump that feels hard when you apply pressure
• Unexplained bruising
• Difficulty breathing
• Night sweats
• Dysphagia (difficulty swallowing)
• Fatigue
• Unexplained weight loss

An accurate diagnosis is important to determine whether the cause of the lump needs treatment.