Painful bumps under the skin can feel tender and uncomfortable. They often come from common skin issues like cysts, acne, boils, or infections.
One frequent cause is cystic acne. This happens when pores get blocked by extra oil, dead skin cells, and bacteria. Hormones play a big role, especially during puberty, stress, or menstrual cycles. The blockage traps bacteria deep inside, sparking strong inflammation that forms a swollen, painful lump. These bumps are red, tender, and can last for weeks. They often show up on the face, jaw, back, or chest.[1]
Cysts are another top reason for these bumps. Epidermoid cysts grow when skin cells get trapped under the surface instead of shedding normally. They fill with a thick, yellow material called keratin. A blocked hair follicle from injury or irritation can start this process. Most cysts are harmless and slow-growing, but they turn painful if they get inflamed, infected, or press on nearby tissue. You might notice a firm lump that leaks smelly fluid if it bursts. They appear on the face, scalp, back, or groin.[4][5][6]
Boils, or furuncles, create painful pus-filled bumps too. Bacteria infect a hair follicle, causing redness, swelling, and a deep lump. These often hurt to touch and may cluster into larger carbuncles. Abscesses work the same way, forming from bacterial buildup anywhere on the body, like the thigh.[7][3]
Infections lead to many under-skin bumps. Bacteria, viruses, or fungi can invade after a cut, burn, or friction. This brings swelling, pain, and pus as the body fights back. Swollen lymph nodes in areas like the thigh or groin signal infection too, feeling like tender lumps.[2][3]
Injury or trauma starts some bumps. Repeated rubbing, scrapes, or wounds damage skin, leading to growths or infected spots. Allergic reactions cause raised, itchy bumps from irritants or meds. Less often, benign tumors like lipomas or fibromas form soft or firm lumps, though they rarely hurt unless pressed.[2][3][4]
If a bump grows, leaks pus, or brings fever, see a doctor. They can check for rare issues like hernias or deeper problems.
Sources
https://londondermatologyclinics.com/cystic-acne-your-guide-to-causes-and-management/
https://nec24.com/uncategorized/what-is-a-lesion
https://mandayahospitalgroup.com/lump-on-the-thigh/
https://www.ummhealth.org/health-library/epidermoid-cysts-of-the-skin
https://rejuvadermatology.com/conditions/cysts-in-venice-fl/
https://www.commonspirit.org/conditions-treatments/skin-cyst
https://www.medanta.org/patient-education-blog/boils-and-carbuncles-causes-prevention-and-care-tips
