blood pressure on one side

Overview

Blood pressure on one side means that the blood pressure reading in one arm is clearly different from the reading in the other arm. Normally, blood pressure is nearly the same in both arms. A difference of more than 10 to 15 points (the top number, called systolic) can sometimes be a sign of a problem with the blood vessels on that side of the body.

A significant difference in blood pressure between arms is not very common. Studies suggest it may affect about 1 in 20 people, but the number can be higher in certain groups, such as older adults or people with vascular diseases.

It can affect anyone, but it is more common in people over 50, those with high blood pressure, diabetes, high cholesterol, or who smoke. It can also occur in younger people with certain conditions like a narrowing of the aorta (coarctation).

Symptoms

Common symptoms

• Many people have no symptoms at all.
• Some may feel dizziness or lightheadedness when using the arm with lower pressure.
• A feeling of weakness, coolness, or numbness in the arm with the lower reading.
• Pain or cramping in the arm during activity (if an artery is narrowed).

Symptoms in children

• In children, a blood pressure difference between arms can be a sign of a birth defect in the aorta (coarctation). Symptoms may include headaches, leg cramps with exercise, or poor growth.
• Often, there are no symptoms, and it is found during a routine check-up.

Symptoms in older adults

• Older adults may experience arm pain or fatigue when using the arm, especially during activities like carrying groceries.
• Some may notice one arm feels colder or looks paler than the other.
• A large difference might be linked to a higher risk of stroke or other heart problems.

Causes

Main causes

• Atherosclerosis: hardening and narrowing of the arteries due to plaque buildup, often in the subclavian artery (the main artery to the arm).
• Blood clots: a clot in the artery of the arm can block blood flow.
• Aortic dissection: a tear in the inner layer of the aorta (the main artery from the heart) – this is a life-threatening emergency.
• Coarctation of the aorta: a narrowing of the aorta present from birth.
• Vasculitis: inflammation of the blood vessels (rare).
• Previous injury or surgery affecting the arm or chest.

Risk factors

• Older age (over 50)
• Smoking or using tobacco products
• High blood pressure (hypertension)
• High cholesterol
• Diabetes
• Obesity
• Family history of heart or blood vessel disease

When to see a doctor

See a doctor urgently if:

• If you have sudden chest pain, shortness of breath, or sudden weakness on one side – call emergency services immediately.
• If you discover a large difference (more than 20 mmHg) in your blood pressure between arms, see your doctor within a few days.

Book a routine appointment if:

• During a routine health check, ask your doctor or nurse to measure blood pressure in both arms at least once.
• If you have known risk factors (smoking, diabetes, high cholesterol) and have not had both arms checked, schedule a visit.

Diagnosis

Your doctor will start by measuring blood pressure in both arms using a standard cuff. If a significant difference is found, they may do further tests to look at the blood vessels.

Tests that may be done

• Blood pressure measurements in both arms, sometimes repeated at different times.
• Ultrasound of the blood vessels (Doppler ultrasound) to see how blood flows in the arteries of the arms and neck.
• Angiography (a special X-ray with dye) to get a detailed picture of the arteries.
• Blood tests to check for underlying conditions like inflammation or cholesterol levels.
• CT or MRI scans to look at the aorta if a more serious cause (like aortic dissection) is suspected.

What to expect at your appointment

Diagnosis is usually straightforward and painless. The doctor will ask about your symptoms, risk factors, and medical history. They may also listen to the arteries in your neck or arm with a stethoscope. Most tests are done as an outpatient, meaning you go home the same day.

Treatment

Treatment depends on the underlying cause. If the difference is small and causes no symptoms, your doctor may simply recommend monitoring. If a blockage or narrowing is found, treatment aims to improve blood flow and prevent complications. This can include lifestyle changes, medications, or procedures.

Self-care at home

• If you smoke, seek help to quit. Smoking damages blood vessels and worsens blockages.
• Control your blood pressure, cholesterol, and blood sugar levels through diet, exercise, and medications as prescribed by your doctor.
• Stay active with regular exercise, like walking or swimming, after checking with your doctor.
• Protect the arm with lower blood pressure from injury or extreme cold.

Medical treatments

Medications may be used to manage underlying risk factors such as high blood pressure, high cholesterol, or diabetes. For example, your doctor may prescribe blood pressure lowering medicines or medicines to reduce cholesterol (statins). They may also recommend antiplatelet medicines (like aspirin or clopidogrel) to prevent blood clots. Always follow your doctor's advice and do not stop medicines without speaking to them first.

When is surgery considered?

If a significant narrowing or blockage is causing symptoms, a doctor may recommend a procedure to open the artery. This could be angioplasty (a tiny balloon inflated in the artery) with or without a stent (a small mesh tube), or bypass surgery to reroute blood flow around the blocked section. These are usually done by a vascular specialist.

Living with this condition

If you have a known blood pressure difference between your arms, keep track of your blood pressure at home using the arm with the higher reading (as advised by your doctor). Continue all regular activities unless your doctor tells you otherwise. Pay attention to any new symptoms like arm pain or dizziness.

Lifestyle tips

• Eat a heart-healthy diet: plenty of fruits, vegetables, whole grains, and lean protein. Limit salt, saturated fat, and sugar.
• Get regular exercise. Aim for at least 150 minutes of moderate activity per week, but check with your doctor first.
• Maintain a healthy weight.
• Limit alcohol intake.
• Manage stress through relaxation techniques, hobbies, or talking with friends or a counsellor.

Diet and exercise

Following a balanced diet low in salt and saturated fat helps manage blood pressure and cholesterol. Exercise improves circulation and heart health. Start slow and increase gradually. If the affected arm becomes painful during exercise, stop and rest. Let your doctor know.

Mental health and emotional wellbeing

Living with a health condition that may require monitoring or treatment can sometimes cause anxiety or worry. It is normal to feel concerned. Talk to your healthcare provider about your worries. They can offer reassurance and connect you with support if needed.

Prevention

You cannot always prevent the underlying causes, but you can reduce your risk of developing significant artery blockages by managing your overall cardiovascular health. This includes not smoking, eating a healthy diet, staying active, and controlling conditions like high blood pressure and diabetes.

Screening programmes

Routine blood pressure checks (including in both arms at least once) are a simple way to screen for this condition. Your doctor may recommend more frequent checks if you have risk factors.

Complications

If left untreated

• Reduced blood flow to the arm, leading to pain, weakness, or even tissue damage (in severe cases).
• Increased risk of stroke or transient ischemic attack (mini-stroke) because of the connection between the arm arteries and the brain.
• If the cause is a narrowing of the aorta (coarctation), untreated high blood pressure can damage the heart, brain, and kidneys.
• In rare cases, a blood clot or severe blockage could lead to loss of the arm (amputation).

Long-term outlook

For most people, a blood pressure difference between arms is not dangerous and can be managed well with lifestyle changes and medical care. When the cause is treated – for example, with medication or a procedure – the outlook is generally very good. Even if the difference persists without symptoms, many people lead full, active lives with regular monitoring.

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