Pulmonary Arterial Hypertension (PAH)

What is pulmonary arterial hypertension (PAH)?

Pulmonary arterial hypertension (PAH) is a specific type of pulmonary hypertension (PH).¹

PH is an umbrella term that describes high blood pressure in the lungs from any cause. PAH is a type of PH and is characterised by increased blood pressure in the blood vessels between the heart and the lungs.² It is a rare disease, and around 55 people per million – nearly 4,000 people – are affected in the UK.^3,4 PAH can occur at any age, although on average people tend to receive a diagnosis between 30-60 years old.

Pulmonary hypertension can be split into five main groups as it can be caused by different factors:⁴

Group 1: pulmonary arterial hypertension
Group 2: pulmonary hypertension associated with left heart disease
Group 3: pulmonary hypertension associated with lung diseases and/or hypoxia
Group 4: pulmonary hypertension associated with chronic pulmonary artery obstruction
Group 5: pulmonary hypertension with unclear and/or multifactorial mechanisms

PAH, or Group 1 PH, is caused when the arteries in the lungs become narrowed, thickened or stiff.¹ The right side of the heart must work harder to push blood through these narrowed arteries, and this extra stress can cause the heart to become less effective at pumping blood to the lungs and body.¹

There are six main types of PAH typically associated to the underlying cause:⁴

Idiopathic PAH: Happens spontaneously, with no obvious cause.⁵ This is the most common type of PAH⁴
Heritable PAH: Caused by genetic changes (mutations) that run in the family⁴
Associated PAH: Develops in association with other medical conditions, including connective tissue diseases like scleroderma (systemic sclerosis) and lupus, congenital heart disease, HIV and liver disease¹
Drug- and toxin-induced PAH: Brought on by exposure to recreational drugs or other toxic substances⁴
PAH with features of venous/capillary (PVOD/PCH) involvement⁴
Persistent PH of the newborn⁴

What are the main symptoms of PAH?⁶

Shortness of breath

Finding you are out of breath going up the stairs, or walking a distance you used to be able to comfortably

Tiredness

Feeling a lack of energy disproportionate to the activity you’re doing

Feeling faint or dizzy

Light-headedness or feeling off-balance

Chest pain (angina)

Tightness, tension, or pain in the chest

A racing heartbeat (palpitations)

A higher-than-normal heart rate, due to the heart working harder

Swelling (oedema) in legs, ankles, feet or tummy (abdomen)

Swollen feet and legs, and noticing indentations from socks, or where you press on your ankles or shins

As the early symptoms of PAH are common to many other conditions, and may only happen after physical activity, it can be difficult to diagnose the disease.^4,7 The onset of PAH can also be so gradual that symptoms go unnoticed for a long time, until the condition is more advanced.⁷ Screening people who are at risk of developing the disease can help lead to earlier diagnosis, support and care.⁴

PAH is a condition that gets worse over time, meaning that a person may experience mild symptoms at first, but eventually, treatment and medical care are needed to improve outcomes.⁷

Our short video below shows why it’s important for patients who are at-risk of developing PAH, or for healthcare professionals who are treating at-risk patients, to Think PAH.

Are you somebody who could be at risk  of developing PAH?

If you’re living with a condition such as congenital heart disease, systemic sclerosis, or other connective tissue diseases, you have a higher risk of developing PAH.⁸ This means it’s important for you to speak to your healthcare practitioner about early detection methods.

Did you know, up to 3 in every 20 people with systemic sclerosis, a form of connective tissue disease, will go on to develop PAH? This means screening and early detection are even more important.⁹

Don’t wait, speak to your consultant about early detection methods.

Are you a healthcare professional?

It’s never too early to use regular detection methods to pick up PAH before symptoms appear and the disease has progressed. Regular use of early detection methods could be particularly valuable for patients in at-risk groups, for example, those with conditions like congenital heart disease, systemic sclerosis, or other connective tissue diseases.⁸

Don’t wait for symptoms to appear. Use regular screening to detect PAH in at-risk patients before disease progression.

Since PAH worsens over time, reducing the time to diagnosis may help mitigate emotional uncertainty and enable timely interventions, ensuring that treatments are applied when they are most effective.¹⁰

If you think you could be at risk, or you treat people who could be, don’t wait – investigate.

Information about chronic thromboembolic pulmonary hypertension (CTEPH)

There are five main groups of pulmonary hypertension, as it can be caused by different factors.¹¹ Group 4 Pulmonary hypertension can sometimes be caused by scars from previous blood clots that narrow or block the pulmonary arteries, this is called chronic thromboembolic pulmonary hypertension (CTEPH). A blood clot that blocks one of the blood vessels that supply your lungs is called a pulmonary embolism (PE).^12,13 Janssen has developed the following materials with input from Thrombosis UK, offering further information about PE. This material is intended for use by people diagnosed with PE.

Information for patients with a confirmed diagnosis of pulmonary embolism (PE).

Recovering from a pulmonary embolism (PE): information for patients with ongoing breathlessness.

Finding your new normal: life after pulmonary embolism (PE).

References

Pulmonary Hypertension Association. Types of Pulmonary Hypertension. Available at: https://phassociation.org/patients/aboutph/types-of-ph/. Last accessed June 2025.
Pulmonary Hypertension Association. About Pulmonary Hypertension. Available at: https://phassociation.org/types-pulmonary-hypertension-groups/. Last accessed June 2025.
Office for National Statistics. UK population. Available at: https://www.ons.gov.uk/. Last accessed June 2025.
Humbert M et al, (2022), 2022 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension; European Heart Journal. Available at: https://doi.org/10.1093/eurheartj/ehac237. Last accessed June 2025.
European Lung Foundation. Pulmonary Arterial Hypertension. Available at: https://europeanlung.org/en/information-hub/lung-conditions/pulmonary-arterial-hypertension/. Last accessed June 2025.
NHS. Pulmonary Hypertension. Available at: https://www.nhs.uk/conditions/pulmonary-hypertension/. Last accessed June 2025.
Armstrong, et al. BMJ Open. 2012;2:e000806. Available at: The trajectory to diagnosis with pulmonary arterial hypertension: a qualitative study | BMJ Open. Last accessed June 2025.
Kovacs, et al. European Respiratory Journal 2024 64(4): 2401324. Last accessed June 2025.
Highland KB, Chakravarty R, Georgi S and Han M (2025). Patient Perspectives and Clinical Insights Into the Diagnostic Journey From Connective Tissue Disease to Pulmonary Arterial Hypertension; The Journal of Rheumatology. Available at Patient Perspectives and Clinical Insights Into the Diagnostic Journey From Connective Tissue Disease to Pulmonary Arterial Hypertension | The Journal of Rheumatology. Last accessed June 2025.
Humbert M, Gerry Coghlan J, Khanna D (2012) Early detection and management of pulmonary arterial hypertension. European Respiratory Review. Available at Early detection and management of pulmonary arterial hypertension - PMC. Last accessed June 2025.
Asthma + Lung UK. Pulmonary hypertension causes. Available at: What causes pulmonary hypertension? | Asthma + Lung UK. Last accessed June 2025.
NHS England. Pulmonary hypertension– Causes. Available at: https://www.nhs.uk/conditions/pulmonary-hypertension/causes/. Last accessed June 2025.
Asthma + Lung UK. What is a pulmonary embolism and what are the symptoms? Available at What are the symptoms of a pulmonary embolism? | Asthma + Lung UK. Last accessed June 2025.