What could cause sudden pain under my fingernail, and how should I address it?

When you suddenly feel pain under your fingernail, it is mostly caused by a minor injury even if you do not see any visible damage. This injury can cause a collection of blood beneath the nail, called a subungual hematoma. The blood pooling under the nail puts pressure on the nail bed, which makes it hurt. Sometimes, a small cut or break can let germs in and lead to an infection, known as paronychia, which also causes pain and may make the skin red or swollen. For mild pain, start by resting your finger and applying a cold compress to reduce any swelling. Keep the finger elevated if possible. Make sure to keep the area clean, and if you notice signs of infection like redness, warmth, or pus, or if the pain becomes severe, consult a doctor. To better understand your symptoms and get personalized guidance, try our free AI symptom checker to help determine if you need immediate care. A healthcare provider can decide if the pain needs a minor procedure, like drainage of the blood or prescription medications to help you heal faster.