Published on: 6/18/2025
What does it indicate if your arm suddenly swells up?
Sudden arm swelling may indicate a serious issue like a blood clot, infection, allergic reaction, or injury and should be evaluated promptly.
Explanation
If your arm swells up quickly without warning, it could be a sign of:
Blood clot (deep vein thrombosis): A clot in the veins can block blood flow, causing rapid swelling, sometimes with pain or discoloration. Infection: A sudden onset of swelling, especially with redness, warmth, or fever, may point to cellulitis or another infection. Allergic reaction: Swelling from a bite, sting, or allergen exposure can appear quickly and may include itching or hives. Injury or trauma: Even if minor, an injury can cause rapid swelling due to bleeding or inflammation under the skin. Lymphedema flare: A sudden buildup of lymph fluid due to a blocked drainage pathway, often after surgery or cancer treatment.
Sudden swelling should not be ignored. If it is severe, worsening, or accompanied by pain, trouble breathing, or chest discomfort, seek immediate medical attention.
(References)
- Ciocon JO, & Galindo-Ciocon D. (1998). Arm edema, subclavian thrombosis, and pacemakers. Angiology, 9555935.
- Reddy SN, Boros MC, & Horrow MM. (2015). Approach to the Swollen Arm With Chronic Dialysis Access. Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine, 26307123.
- Avrahami R, Gabbay E, Bsharah B, Haddad M, Koren A, Dahn J, & Zelikovsky A. (2004). Severe lymphedema of the arm as a potential cause .... Lymphology, 15693538.
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