Swollen lymph nodes in the armpit typically feel like small, round or oval lumps just beneath the skin, often described as rubbery or firm with a smooth surface. They’re usually tender to the touch, and most shift slightly when you press on them. Normal lymph nodes are too small to feel, so if you’re noticing one, it’s already larger than usual.
Where You’ll Feel Them
Your armpit contains five groups of lymph nodes spread across different areas of the axillary space. You’re most likely to feel a swollen node in the central part of your armpit, nestled in the soft fatty tissue at the base. Some people notice them closer to the chest wall (toward the front of the armpit) or along the inner edge of the upper arm. Depending on which nodes are reacting, the lump may sit shallow enough to spot in a mirror or deep enough that you only find it by pressing firmly into the armpit with your fingers.
Texture, Size, and Mobility
A swollen lymph node from a common infection or immune response tends to feel soft to slightly firm, with a rubbery quality similar to a grape or a small bouncy ball. It usually moves a little under your fingertip when you press it, sliding away from direct pressure rather than staying locked in place. This mobility is a reassuring sign. Most reactive nodes measure roughly 1 to 2 centimeters, about the size of a pea to a kidney bean, though they can grow larger with a significant infection.
Nodes that feel rock-hard, have an irregular or lumpy shape, or seem stuck to the tissue around them behave differently. Fixed nodes that don’t budge when pressed, or clusters that feel matted together like a clump, warrant closer evaluation. These features don’t automatically mean something serious, but they fall outside what a typical reactive node looks and feels like.
Pain and Tenderness
Tenderness is one of the most common things people notice first, sometimes before they even feel the lump itself. Infected or inflamed nodes are often sore when pressed or even when your arm moves against them during the day. The skin over the area may feel warm, and in more advanced infections (a condition called lymphadenitis), you might see redness or red streaking on the skin above the node.
Painless lumps are common too, and they aren’t necessarily more dangerous. Mildly enlarged nodes from a recent vaccination or a low-grade immune response can swell without causing any discomfort. That said, a painless node that is hard, irregular, and doesn’t move is the combination that raises the most clinical concern for possible malignancy, even though no single feature on its own reliably predicts cancer.
Why Your Armpit Nodes Swell
The most common reason is a nearby infection. A cut, razor nick, or infected hair follicle on your hand, arm, or chest can trigger the armpit nodes to enlarge as they filter and fight off bacteria. Upper respiratory infections, skin conditions like eczema, and even dental infections occasionally cause armpit swelling because these nodes drain a wide territory.
Vaccination is another frequent trigger. COVID-19 vaccines in particular became well known for causing noticeable armpit swelling on the same side as the injection. This can happen after any dose and typically resolves within six to ten weeks. Flu shots and other upper-arm injections can do the same, though usually less dramatically.
Less common causes include autoimmune conditions, certain medications, and cancers such as lymphoma or breast cancer that spread to the axillary nodes. In these cases, the nodes often grow gradually, feel harder, and may not be tender.
Lymph Node vs. Cyst vs. Lipoma
Not every lump in the armpit is a lymph node. Cysts feel round, firm, and well-defined, but unlike lymph nodes, they tend to stay fixed in place when you press them. They’re usually painless unless they become infected. A lipoma (a benign fatty lump) feels soft and doughy, sits just under the skin, and moves easily. It grows slowly over months or years and doesn’t become tender the way an inflamed lymph node does.
Swollen lymph nodes are softer than cysts, have that characteristic rubbery give, and shift slightly under pressure. If you’re unsure what you’re feeling, the combination of tenderness, recent illness or vaccination, and a lump that appeared within the past week or two points toward a reactive lymph node rather than a cyst or lipoma.
Features That Need Attention
Most swollen armpit nodes shrink back to normal within two to four weeks once the triggering infection or irritation clears. A few characteristics are worth taking seriously if you notice them:
- Hard, irregular texture that feels more like a rock than a grape
- Fixed position where the lump doesn’t move at all under your fingers
- Matting, where multiple nodes feel stuck together in a clump
- Persistent growth over several weeks without an obvious cause
- Asymmetry, meaning one armpit has noticeably enlarged nodes while the other does not, with no clear explanation like a recent injection
Any single one of these features can show up in benign conditions too. Infections can cause matting, and reactive nodes sometimes persist for weeks. But the combination of painless, hard, immobile, and growing is the pattern that prompts further workup, typically starting with an ultrasound. On imaging, a healthy node has a thin outer layer (3 mm or less) and a visible fatty center. Loss of that fatty center, a rounded shape, or uneven thickening of the outer cortex are the changes that raise concern.