why are my fingers swollen

Infection- Infections, such as cellulitis or a finger abscess, can cause localized swelling, redness, and pain. 

Fluid Retention: Conditions like heart failure, kidney disease, or liver disease can result in fluid retention, leading to swelling in various parts of the body, including the fingers. 

Allergic Reaction: Allergic reactions to certain foods, medications, or insect bites can cause swelling, including in the fingers. 

Medication Side Effects: Certain medications may cause fluid retention as a side effect, leading to swelling in various body parts, including the fingers.