Possible Causes of One-Sided Leg Swelling

Lymphedema

Lymphedema occurs when the lymphatic system cannot properly drain fluid from the tissues.

This can happen after:

• cancer treatment
  
  
• surgery involving lymph nodes
  
  
• radiation therapy
  
  
• trauma
  
  
• infection
  
  

Because the lymphatic system on one side of the body may be affected more than the other, swelling can appear in only one leg or one arm.

Lymphedema swelling often develops gradually and may feel heavier, tighter, or firmer over time.

Venous Insufficiency

Another common cause of leg swelling is venous insufficiency, where the veins have difficulty returning blood to the heart.

This can lead to:

• ankle swelling
  
  
• skin discoloration
  
  
• heaviness in the legs
  
  
• swelling that worsens after long periods of standing or sitting
  
  

Venous swelling may affect both legs, but sometimes one side is worse than the other.

Injury or Inflammation

Swelling in one leg can also occur after:

• muscle injury
  
  
• joint inflammation
  
  
• infection
  
  
• trauma
  
  

These causes often come with pain, redness, or warmth in the affected area.

Blood Clot (Deep Vein Thrombosis)

Sudden swelling in one leg can sometimes be caused by a blood clot, called a deep vein thrombosis (DVT).

This condition requires immediate medical evaluation.

Signs may include:

• sudden swelling
  
  
• pain or tenderness
  
  
• warmth in the leg
  
  
• skin discoloration
  
  

If these symptoms occur suddenly, medical attention should be sought right away.

When Swelling Persists

If swelling in one leg does not resolve, continues to return, or gradually worsens over time, it may indicate a lymphatic or vascular issue.

Early evaluation can help determine the cause and guide appropriate treatment.

Treatment Depends on the Cause

Different types of swelling require different treatments.

For individuals diagnosed with lymphedema, treatment may include:

• manual lymphatic drainage
  
  
• compression therapy
  
  
• exercise to stimulate lymphatic flow
  
  
• skin care
  
  

These therapies help support the lymphatic system and reduce swelling.

The Bottom Line

Swelling in one leg is a common symptom that can have several causes.

Because swelling may involve the lymphatic system, veins, or other medical conditions, evaluation by a healthcare professional is important to determine the underlying cause.

When to Seek an Evaluation

If swelling in one leg is persistent, worsening, or unexplained, consultation with a healthcare professional experienced in lymphedema and swelling disorders can help identify the cause and develop a treatment plan.