These include:
Recent surgery or hospitalization
Long periods of immobility
Long-distance travel
Previous blood clots
Certain cancers
Pregnancy and the postpartum period
Some hormone-containing medications
Certain inherited or acquired clotting disorders
Being aware of these risk factors can help people recognize when new leg swelling deserves particular attention.
10. Don't Massage a Leg If a Blood Clot Is Suspected
Another important point is that unexplained one-sided swelling should not be aggressively massaged in an attempt to “break up” the swelling.
If DVT is a possibility, medical evaluation should come first.
Likewise, avoid relying on internet remedies, compression products, or medications to treat unexplained swelling without appropriate medical advice.
The correct treatment depends entirely on the underlying cause.
When Should You Contact a Doctor?
Seek medical advice for new or unexplained leg swelling, particularly when it affects only one leg or is accompanied by redness, warmth, pain, or tenderness.
Seek urgent care when symptoms are rapidly worsening or accompanied by fever or significant illness.
And if leg swelling occurs together with sudden breathing difficulty, chest pain, coughing up blood, fainting, or severe weakness, seek emergency medical care immediately.
The Bottom Line
The leg shown in the image has visible swelling and significant skin discoloration, but a photograph cannot determine the diagnosis.
It would be misleading to claim that these changes are definitely caused by sleeping in a particular position.
Persistent or sudden leg swelling can have many causes, including cellulitis, DVT, venous disease, injury, and fluid-retention disorders. Some are relatively minor, while others can become serious without treatment.
The safest approach is simple:
Don't ignore a new swollen, red, hot, or painful leg.
And don't assume that an alarming change is simply the result of how you slept.
Your body can sometimes signal a problem through changes that seem small at first. Recognizing those changes—and getting the right medical evaluation when necessary—is far more important than trying to diagnose the cause from a viral photograph.