My legs swell up: what should I know?

Fluid can collect around the ankles after long periods of sitting or standing, in hot weather, or when the leg veins do not return blood efficiently. Varicose veins may cause heaviness, aching, or swelling that is worse later in the day. Injury, infection, and some medicines can affect one leg or both. Swelling in both legs may also occur when the heart or kidneys are not managing fluid normally. Obesity can add pressure to veins and make swelling more noticeable. The pattern, speed of onset, skin changes, breathlessness, and other symptoms help a clinician work out the cause.

Keep a simple record of when swelling appears, whether it affects one or both legs, and whether it improves overnight. Move your ankles and walk gently during long sitting, avoid tight clothing around the legs, and raise the legs when resting if this is comfortable. Protect swollen skin from cracking and check for redness or sores. Do not start compression socks or change fluid tablets without advice, because the right choice depends on circulation and the underlying cause. Book an assessment when swelling persists, recurs, or follows a new medicine.

Get urgent help for sudden swelling in one leg, especially with calf pain, warmth, redness, or tenderness. Seek emergency care for swelling with sudden breathlessness, chest pain, coughing blood, fainting, or severe weakness. Prompt review is also needed for rapidly worsening swelling, fever, a painful wound, or breathlessness when lying down. These patterns can signal a clot, infection, or significant fluid problem.

Is the swelling related to veins, a medicine, injury, heart, or kidney function? Should I have blood tests or an ultrasound? Are compression socks and leg elevation safe for me?