The side effects of a lump in the neck depend on its underlying cause. For instance, a benign lump may cause minor discomfort or be asymptomatic. However, if the lump is due to an infection or inflammation, it may lead to pain, swelling, redness, or fever. If the lump is cancerous, it might cause persistent pain, weight loss, difficulty swallowing, or changes in voice. Any concerning symptoms should be evaluated by a healthcare provider.