A lump under the jaw or along the neck that remains for more than three weeks may be a sign that medical attention is needed, according to health guidelines. These lumps often appear after a cold or sore throat and may seem to go away on their own. However, if the lump persists beyond three weeks, it could signal a more serious condition. Warning signs include a hard, painless texture, a size larger than 2 centimeters, or a location above the collarbone. Tests such as ultrasound, fine-needle aspiration, or biopsy can help determine whether the lump is benign or linked to conditions like lymphoma or head and neck cancer. Lymph nodes in the neck typically swell in response to infections, such as a cold or sore throat. These nodes usually become tender and then shrink as the infection clears. However, if the swelling lasts more than three weeks, it may indicate a more concerning issue. In adults, this time frame is a key indicator that a medical evaluation should be sought, regardless of the node's size or whether it is painful. The absence of pain combined with prolonged swelling can be a red flag. When a sore throat or ear infection has resolved and a fever has gone away, it becomes harder to link a persistent lump to the same infection. The body usually finishes its healing process by the third week. If the swelling continues to grow, exceeds 2 centimeters, or is located above the collarbone, an infectious cause becomes less likely. Other concerning symptoms include unexplained weight loss, night sweats, unusual fatigue, or difficulty swallowing. These symptoms, when combined with a persistent neck lump, especially in those over 40, should not be ignored. A lymph node that is part of a normal immune response is usually soft, movable, and painful to touch. In contrast, a suspicious lymph node is often hard, fixed in place, and unexpectedly painless. These concerning nodes are typically found in specific areas, such as above the collarbone or along the neck's jugular chain. Risk factors like smoking and alcohol use are often considered by doctors when evaluating a persistent neck lump. This is why healthcare providers often ask about these habits during a physical exam. If a suspicious lymph node is found, a doctor usually starts with a cervical ultrasound, a non-invasive test that can assess the size, shape, and structure of the node. If the results are unclear, a CT scan may be used to look more broadly at the neck and throat. When uncertainty remains, further tests like fine-needle aspiration—where a small sample of cells is taken—or a surgical biopsy, which removes a larger tissue sample for analysis, may be performed. Persistent neck lumps can sometimes be an early sign of serious conditions like lymphoma or head and neck cancers, which affect areas such as the tonsils, pharynx, larynx, or tongue. These cancers are among the most common in France, with around 20,000 new cases diagnosed each year. A firm, painless, and fixed lymph node that lasts more than three weeks should prompt a visit to an ENT specialist, ideally accompanied by an ultrasound. While not every neck lump is cause for alarm—many are due to simple infections like a cold or ear infection—it's wise to consult a doctor if a lump remains for more than three weeks. This period is generally when the body would have resolved a temporary inflammation. If the lump persists beyond this time, a medical evaluation, possibly including an ultrasound or biopsy, can help determine the cause and allow for early treatment if needed.