Sudden swelling and pain in the fingertips may be caused by hematoma of the fingers, skin allergies, onychomycosis, osteoarthrosis and other reasons. 1. Finger hematoma: It may be due to finger trauma, after squeezing or collision, resulting in finger blood vessels or capillaries rupture, blood leakage into the middle of the tissue of the fingertip, so the fingertip suddenly swollen and painful. 2. Skin allergy: due to eating allergic food or contact with some irritating substances, may lead to sudden swelling and pain in the fingertips, accompanied by localized intense itching of the skin. 3. Inguinitis: Sudden swelling and pain in the fingertips may also be caused by inguinitis, which can lead to swelling and pain in the fingertips under the stimulation of inflammation, and pus may also appear. 4. Osteoarthritis: Mostly seen in manual laborers or the elderly, due to frequent wear and tear of the bone joints, osteoarthritis will be formed over a long period of time, so there will be a sudden swelling and pain in the fingertips. If your fingers are suddenly swollen and painful, you should go to the hospital in time for the appropriate examination, make a clear diagnosis, and standardize the treatment under the guidance of the doctor.