The characteristic symptom of peripheral artery disease is intermittent claudication, meaning aching, cramping, heaviness or pain in a leg muscle that appears during walking or another form of exertion and improves after several minutes of rest. The symptom occurs because narrowed arteries cannot increase blood flow sufficiently when exercising muscles require more oxygen. The discomfort commonly affects the calf, although the thigh, buttock or hip can be involved depending on the anatomical location of arterial disease.
It may affect one or both legs and can range from mild to severe. The predictable relationship between exertion and rest is an important clinical clue. NHS guidance notes that many people with PAD have no symptoms, while others develop this characteristic exercise-related leg pain.
PAD can also produce changes in the skin and tissues of the affected limb because chronic reduction in arterial blood supply deprives tissues of oxygen and nutrients. The skin may become unusually pale or develop a blue or other altered colour, and it may become smooth, thin and shiny. Hair growth on the legs and feet may decrease, while toenails can become brittle and grow more slowly.
The affected limb may feel cooler than expected because reduced arterial flow limits the delivery of warm blood from the body's core. These physical signs are not individually diagnostic because similar changes can occur in other conditions, but their combination with weak pulses or exercise-related pain can support the presence of arterial insufficiency.
Weakness, numbness and reduced exercise capacity can occur in PAD. The weakness is partly related to inadequate oxygen delivery to working muscles and, in advanced disease, loss of muscle mass may develop. Numbness can reflect chronic ischaemia affecting nerves, although neurological disorders, spinal disease and other conditions can cause similar sensations. In men, erectile dysfunction can sometimes occur because penile blood vessels are also affected by systemic vascular disease.
PAD can therefore present through symptoms that do not initially seem related to leg circulation. A careful assessment considers the distribution, timing and triggers of symptoms rather than assuming that all leg pain represents PAD. Musculoskeletal problems such as arthritis or spinal stenosis can also cause exertional leg discomfort but typically have different patterns and associated features.
In more advanced PAD, reduced circulation can cause wounds or ulcers on the feet and legs that heal slowly or fail to heal. Normal tissue repair requires oxygen, nutrients, immune activity and adequate blood flow, so severe arterial insufficiency can make even a small injury clinically important. A person may therefore develop a persistent sore on a toe, foot or lower leg following minor trauma.
In diabetes, the risk can be increased further because neuropathy may reduce awareness of injury while vascular disease limits healing. Persistent ulcers are particularly important because they can become infected and progress to tissue loss. The presence of a non-healing wound in someone with suspected PAD warrants medical assessment rather than being treated as an ordinary minor skin injury.
Chronic limb-threatening ischaemia represents a severe form of arterial insufficiency in which blood supply is inadequate even when the person is resting. Symptoms can include persistent severe burning or aching pain in the feet or legs, often worse at night or when the limb is elevated. Patients may obtain some relief by placing the leg in a dependent position because gravity can modestly increase arterial perfusion.
The skin may become pale, smooth, shiny and dry, and ulcers may fail to heal. Severe tissue ischaemia can progress to gangrene, in which tissue dies because of prolonged inadequate blood supply and may become infected. NHS guidance describes severe resting pain, non-healing wounds and tissue colour changes as important signs of critical limb ischaemia.
Symptoms that appear suddenly or deteriorate rapidly are different from the usual slowly progressive pattern of PAD and may indicate acute limb ischaemia. This can occur when a blood clot suddenly blocks an already narrowed artery or when an embolus travels into a limb artery. The affected limb can become suddenly painful, cold, pale or discoloured, numb and weak, with markedly reduced or absent pulses.
This is a vascular emergency because prolonged interruption of arterial blood flow can result in irreversible tissue damage. The distinction between chronic intermittent claudication and sudden severe ischaemia is therefore clinically important: gradual exertional symptoms can indicate chronic PAD, whereas sudden severe symptoms require immediate emergency assessment.
PAD can be clinically silent, particularly in its earlier stages. Some people have arterial narrowing detected during investigation or vascular assessment without experiencing classic claudication. Others may unconsciously reduce their activity to avoid provoking symptoms and therefore not recognise the relationship between exercise and pain. People with diabetes or neurological impairment may also have reduced sensation and fail to notice injuries or discomfort. For this reason, absence of leg pain does not necessarily exclude PAD. Clinicians may look for weak or absent peripheral pulses, skin changes, ulcers and other physical signs and may measure the ankle-brachial pressure index, which compares blood pressure at the ankle with that in the arm.
The pattern of symptoms helps distinguish PAD from other causes of leg discomfort. Claudication usually occurs predictably after a similar amount of walking and improves with rest, whereas pain caused by osteoarthritis may relate more closely to joint movement and weight-bearing, and neurogenic claudication from spinal stenosis can vary with posture and may improve when sitting or bending forwards. Venous disease can cause swelling and aching but has a different vascular mechanism. The combination of exertional pain, reduced pulses, skin changes and delayed wound healing is more suggestive of arterial insufficiency. Because PAD is associated with increased risk of heart attack and stroke, its symptoms also have significance beyond the legs.
