What Is Peripheral Arterial Disease (PAD)? Symptoms, Stages, and When to Act

A plain-language guide for patients and families navigating a PAD diagnosis.

Peripheral arterial disease (PAD) affects an estimated 8 to 12 million people in the United States alone, yet many go undiagnosed until symptoms have already become serious. Understanding what PAD is, how it progresses, and what warning signs to watch for can make a meaningful difference in what treatment options remain available.

If you or someone you love has been told they have PAD, or if you are trying to understand symptoms that have not yet been explained, this guide is a starting point.

What Is Peripheral Arterial Disease?

Peripheral arterial disease is a circulatory condition in which the arteries supplying blood to the legs become narrowed or blocked. The most common cause is atherosclerosis: a buildup of plaque inside the artery wall made of fat, calcium, and inflammatory tissue.

As plaque accumulates, blood flow decreases. The tissues of the leg and foot receive less oxygen and fewer nutrients. Over time, this can progress from manageable discomfort to a condition that threatens the limb itself.

Who Is Most at Risk for PAD?

PAD is most common in people over 60, but it can develop earlier with certain risk factors:

Long-term smoking or significant smoking history

Type 1 or Type 2 diabetes, especially with poor blood sugar control

High blood pressure or elevated cholesterol over many years

Chronic kidney disease

Family history of vascular or heart disease

Having more than one of these risk factors accelerates how quickly the disease progresses. If you identify with this list and have not had a vascular screening, it is worth discussing with your doctor.

The Three Stages of PAD

Stage 1: No Symptoms Yet

Plaque is building, but the body is compensating. Most people at this stage are unaware they have PAD. It is often caught incidentally through an ankle-brachial index (ABI) test done for another reason.

Stage 2: Claudication

Legs cramp, ache, or tire during walking, then recover with rest. The narrowed arteries can meet baseline needs but not the demands of activity. Many patients manage claudication well with medication and supervised exercise.

Stage 3: Chronic Limb-Threatening Ischemia (CLTI)

Blood flow is now critically reduced even at rest. This stage brings rest pain at night, wounds that will not heal, and in the most severe cases, tissue loss. CLTI requires urgent vascular evaluation.

Symptoms of Peripheral Arterial Disease to Watch For

PAD advances quietly. Early symptoms are easy to dismiss. Warning signs include:

Leg or calf pain, cramping, or fatigue during walking that goes away with rest
Coldness, numbness, or color changes in the lower leg or foot
Wounds or sores on the feet or legs that are slow to heal
Pain in the foot or toes that wakes you at night
A weak or absent pulse in the leg or foot

If you are experiencing any of these, especially a non-healing wound, do not wait. Seek vascular evaluation promptly. Delays in treatment are consistently associated with worse outcomes.

Any wound on the foot or lower leg in a patient with known PAD or diabetes that has not improved after four to six weeks of wound care warrants urgent vascular assessment.

When Standard Treatment Has Limits

For many patients, PAD is manageable with medication, lifestyle changes, and revascularization procedures like bypass surgery or stenting. These approaches work well when the disease is caught early enough and the anatomy allows it.

But in patients where disease has advanced into the smaller vessels of the calf and foot, or where prior procedures have already been exhausted, conventional revascularization may no longer be feasible. This is called no-option CLTI, and it is more common than most patients realize.

For these patients, investigational research programs are studying biological approaches that may help support blood flow and assist the body's natural repair processes. Access pathways exist in Florida, Toronto, and internationally through physician-supervised programs.

The Most Important Step You Can Take Now

Ask for an ABI test at your next appointment if you have not had one. It is non-invasive, takes minutes, and is one of the clearest early signals of arterial disease.

If you have already been told that no further surgical options remain, that is not the end of the conversation. Investigational research pathways exist specifically for patients in that situation. Asking your physician about them is a reasonable and appropriate next step.

Educational content only. Not medical advice. ACP-01 is an investigational therapy and has not been approved by the FDA or Health Canada.