I flew back from Australia last week and now I suddenly can't catch my breath. What could it be?

Sudden shortness of breath after a long-haul flight is a symptom that requires immediate medical evaluation. Because you recently sat still for an extended period on a flight from Australia, doctors take this seriously to rule out a blood clot in the lungs.¹²³

Urgent Action Required

• Call 999 or go to A&E immediately if you are gasping for air, struggling to speak in full sentences, have chest pain or tightness, feel dizzy or faint, are coughing up blood, or notice your lips or skin turning pale, blue, or grey.¹²³
• Contact NHS 111 or your GP urgently if your breathlessness came on suddenly, even if it feels mild or you do not have other severe symptoms. Tell them straight away that you recently took a long-haul flight.¹²

Potential Causes

• Pulmonary Embolism (PE): Prolonged sitting on long flights slows blood flow in your legs, which can cause a blood clot known as deep vein thrombosis (DVT). If a piece of that clot breaks off and travels to the lungs, it blocks blood flow and causes sudden breathlessness. This risk remains elevated for several weeks after landing.
• Respiratory Infections: Recirculated cabin air and close quarters make it easy to catch a viral or bacterial chest infection, such as COVID-19, flu, or pneumonia. These illnesses can inflame your airways and make breathing difficult.
• Asthma or Airway Irritation: Extremely dry cabin air can irritate sensitive airways. Exposure to new allergens, cold weather, or pollution back home can also trigger an unexpected asthma flare-up.
• Heart Conditions: Long-haul travel, dehydration, and shifts in cabin pressure can occasionally trigger an irregular heartbeat (arrhythmia) or put extra strain on the heart, leading to sudden breathlessness.
• Anxiety or Panic Attacks: Severe jet lag, exhaustion, and post-travel stress can trigger hyperventilation and a sudden feeling that you cannot get enough air. However, doctors always rule out physical causes like a blood clot first.^12345678910

What to Watch For

While waiting to be assessed by a medical professional, take note of any accompanying signs to share with the doctor:

• Leg symptoms: Pain, tenderness, swelling, warmth, or redness in one leg, especially in the calf.
• Chest symptoms: Sharp chest pain that gets worse when you take a deep breath or cough.
• Heart rate: A racing, pounding, or fluttering heartbeat.
• Infection signs: A new fever, chills, sore throat, or a cough producing phlegm.¹²³⁴⁵⁶

Learn more Are you currently having any other symptoms like chest pain, leg swelling, or a cough? Knowing this—along with whether you feel safe to seek urgent medical care right now—can help me give you more relevant information.

Seek immediate emergency medical care by calling 999 or going to your nearest A&E. Sudden shortness of breath after a long-haul flight is a primary warning sign of a pulmonary embolism (PE), which is a life-threatening blood clot in the lungs. Do not drive yourself to the hospital.¹

Why This Requires Urgent Action

• Pulmonary Embolism (PE): Sitting still for many hours on a long flight from Australia significantly increases the risk of a blood clot forming in your leg, known as deep vein thrombosis (DVT). This clot can break loose and travel to your lungs days or even weeks after you land, blocking blood flow.
• Immediate Danger: A pulmonary embolism requires urgent hospital tests and blood-thinning treatment to prevent serious complications.¹²³⁴

Red Flag Symptoms

While any sudden difficulty breathing after a long flight requires an emergency assessment, tell paramedics or hospital staff immediately if you also notice any of these signs:¹

• Chest or Upper Back Pain: Sharp, stabbing pain that gets worse when you take a deep breath or cough.
• Heart Changes: A very fast, pounding, or irregular heartbeat.
• Coughing: An unexplained cough, especially if you cough up blood or blood-streaked phlegm.
• Dizziness: Feeling lightheaded, dizzy, or faint.
• Leg Symptoms: Pain, swelling, tenderness, warmth, or skin colour changes in one leg, usually in the calf.¹²³⁴⁵⁶

Other Potential Causes

Doctors will rule out a blood clot first. Once a pulmonary embolism is excluded, they may look into other post-travel possibilities:¹

• Respiratory Infections: Viral or bacterial chest infections, such as COVID-19, flu, or pneumonia, are common after crowded flights and airport travel.
• Heart Issues: Prolonged travel stress, dehydration, and lower cabin oxygen can sometimes trigger underlying heart conditions.
• Asthma Flare-Up: Dry cabin air and new environments can irritate airways and cause sudden tightness.¹²³⁴

Review the official NHS Pulmonary Embolism Guidance for full details on emergency signs and what to bring to A&E.¹Learn more Are you experiencing any other symptoms right now, such as chest pain, a racing heart, or swelling in one leg? Once you have been safely assessed by a medical professional, I can help explain any tests or next steps they discuss with you.

Sudden shortness of breath one week after a long-haul flight requires immediate medical evaluation to rule out a pulmonary embolism (a blood clot in the lung). Because long flights from Australia involve prolonged sitting, you face a higher risk of blood clots for up to a month after landing.¹

Immediate Warning Signs (Seek Emergency Care)

Call emergency services (999 in the UK) or go to the nearest A&E immediately if your breathlessness is sudden or paired with any of these symptoms:

• Chest pain or tightness. This often feels sharp and gets worse when you take a deep breath or cough.
• Coughing up blood. Even small streaks of blood in your spit need urgent assessment.
• Fast heart rate or dizziness. Feeling lightheaded, faint, or noticing your heart racing can signal reduced oxygen or blood flow.
• Pain or swelling in one leg. A warm, red, or tender calf or thigh points to a deep vein thrombosis (DVT), which can travel to the lungs.¹

Potential Causes

While a blood clot is the most urgent concern, a doctor will also check for other common post-travel issues:

• Pulmonary embolism (PE). Sitting in a cramped seat slows blood flow in your legs, allowing clots to form and travel to your lungs days or weeks later.¹
• Respiratory infection. Crowded airports and dry cabin air make it easy to catch a viral or bacterial chest infection, such as COVID-19, the flu, or pneumonia.¹²
• Asthma or airway irritation. Breathing dry, recycled air at low cabin pressure can irritate sensitive airways and trigger a delayed flare-up.¹
• Heart strain. The stress, dehydration, and lower oxygen levels of a long flight can occasionally unmask an underlying heart issue.¹²

What to Do Right Now

• Get assessed today. Do not wait to see if the breathlessness passes on its own. Contact NHS 111 for urgent advice or visit an urgent care centre if your symptoms are mild, and go straight to A&E if you feel unwell or have any warning signs above.
• Rest in a comfortable position. Sitting upright often makes breathing easier than lying flat while you wait for medical help.
• Share your travel history. Tell the medical team immediately that you took a long-haul flight from Australia last week so they prioritize ruling out a clot.¹²³⁴

Learn more If you are safe and currently awaiting evaluation, let me know if you have any other symptoms (like a fever, cough, or leg pain) or existing medical conditions, and I can help you prepare details for your doctor.

• Pulmonary Embolism (PE): Sudden shortness of breath after a long-haul flight from Australia (which takes roughly 15 to 24+ hours) is a classic warning sign of a blood clot that formed in a deep vein (DVT) during prolonged immobility and travelled to your lungs. This is a medical emergency. ¹
• Respiratory Infection or Viral Illness: Picking up a cold, COVID-19, influenza, or a lower respiratory tract infection in a crowded airport or during a very long flight can cause sudden or escalating breathlessness days later.
• Asthma or Bronchospasm: Dry cabin air, fatigue, or stress from extreme jet lag can trigger an underlying or newly aggravated airway reaction.
• Anxiety or Panic: The overwhelming physical shock of severe jet lag, exhaustion, or sudden health anxiety can manifest as hyperventilation and a feeling of air hunger.

What You Should Do Immediately

Because sudden breathlessness after a long flight can be life-threatening (like a PE), you should seek urgent medical attention straight away —call 999 (in the UK), go to your nearest A&E, or call emergency services.¹

Look out for red-flag symptoms that require immediate emergency care:

• Sharp or crushing chest pain (which may worsen when you breathe in)
• A fast or pounding heart rate
• Coughing up blood
• Swelling, pain, warmth, or redness in one of your calves or legs
• Dizziness, lightheadedness, or fainting¹

If you are able to reply right now:

• Are you experiencing any chest pain, rapid heartbeat, or leg swelling?
• Did you have any other symptoms (like a cough, fever, or dizziness) start since landing?

Sudden shortness of breath after a long-haul flight (like the multi-hour journey from Australia) is a symptom that requires prompt medical attention.

⚠️ URGENT: When to Seek Emergency Care

Go to the nearest emergency department or call emergency services immediately if your shortness of breath is accompanied by any of these warning signs:

• Chest pain, tightness, or pressure (especially if it radiates to your arm, back, neck, or jaw)
• Coughing up blood
• Dizziness, lightheadedness, or fainting
• A rapid or irregular heartbeat
• Blue, gray, or pale lips, face, or nail beds¹²

What Could It Be?

1. Pulmonary Embolism (PE) – High Priority / Medical Emergency
   • What it is: A blood clot (often originating as a deep vein thrombosis, or DVT, in the deep veins of your leg from prolonged sitting during a very long flight) breaks loose and travels to the lungs, blocking an artery.
   • Why it fits: Flying from Australia involves extreme immobility for 15+ hours, which is a classic risk factor for blood clots.
   • Associated signs: Sudden breathlessness, sharp chest pain (often worse when taking a deep breath), rapid pulse, or a swollen, tender, or warm calf/leg.
   • Guidance: According to the CDC Travel and Blood Clots Guide, sudden breathlessness post-travel should never be brushed off as mere jet lag or fatigue.¹²
2. Respiratory Infection (e.g., Pneumonia or Severe Viral/Bacterial Bronchitis)
   • What it is: Crowded airport terminals, long-haul cabin air circulation, and deep fatigue make it very easy to pick up a respiratory bug.
   • Associated signs: A cough, fever, chills, fatigue, or thick mucus.¹
3. Post-Travel Exhaustion or Severe Dehydration
   • What it is: Extreme sleep schedule disruption (jet lag) combined with cabin dehydration can occasionally manifest as heavy sluggishness or feeling like you cannot catch a full breath, though it is less commonly a sudden, sharp inability to breathe.

What You Should Do Right Now

• Do not wait to see if it passes. If you are struggling for breath, contact a doctor urgently or go to the nearest emergency room.
• When you speak with medical staff, explicitly mention that you just flew back from Australia last week so they can immediately screen for a blood clot or pulmonary embolism.¹

Are you experiencing any chest pain, a rapid heartbeat, or swelling/pain in your leg or calf, or have you noticed a fever or cough?

• Pulmonary Embolism (PE) / Deep Vein Thrombosis (DVT): A blood clot can form in the deep veins of your leg during a long-haul flight (like the long journey from Australia) due to prolonged immobility. If a piece of that clot breaks off and travels to your lungs, it causes sudden shortness of breath, chest pain, or a rapid heart rate. This is a medical emergency.
• Asthma or Bronchospasm: Dry cabin air, fatigue, or a sudden change in climate/air quality can trigger an airway constriction or flare-up of underlying asthma.
• Severe Dehydration or Exhaustion: The physical toll of crossing multiple time zones and enduring a 20+ hour travel itinerary can manifest as sudden cardiovascular strain, dizziness, or air hunger.
• Post-Viral or Respiratory Infection: You may have picked up a bug (such as a cold, flu, or COVID-19) during the crowded airport/plane journey, which is now settling into your chest or airways.
• Anxiety or Panic: The disorientation of severe jet lag, physical stress, or sudden health anxiety can trigger hyperventilation, making it feel like you cannot catch your breath.

⚠️ What You Should Do Right Now

Because sudden shortness of breath—especially following a long-haul flight—can be a sign of a pulmonary embolism, you should seek immediate medical evaluation:

1. Call emergency services (999 in the UK or 112 in Europe/mobile) or go straight to the nearest Accident & Emergency (A&E) department.
2. Seek urgent care if you notice any accompanying red-flag symptoms:
   • Sharp chest pain (often worse when you breathe in)
   • A cough (sometimes coughing up blood)
   • Swelling, warmth, or pain in one of your calves or thighs (a sign of DVT)
   • Dizziness, lightheadedness, or fainting

Are you experiencing any chest pain, coughing, or swelling in your legs, and are you able to sit upright comfortably right now?

I'm concerned about this, particularly because you've recently taken a long-haul flight from Australia.

Sudden difficulty catching your breath after a long-haul flight can be a sign of a blood clot in the lung (pulmonary embolism, or PE). This is something that needs to be ruled out urgently.

What could be causing it?

There are several possibilities:

1. Pulmonary embolism (blood clot in the lung) – Long periods of sitting during flights increase the risk of blood clots forming in the legs. A clot can travel to the lungs and cause sudden breathlessness. This can be life-threatening.
2. Deep vein thrombosis (DVT) – A blood clot in the leg, which can cause swelling, pain, tenderness or warmth, sometimes without obvious symptoms.
3. Chest infection or pneumonia – Can cause breathlessness, coughing, chest discomfort and fever.
4. Heart-related problems – Some heart conditions can cause sudden shortness of breath.
5. Asthma or respiratory irritation – Can also cause difficulty breathing.

(Please seek emergency medical help now)

Because you've developed sudden breathlessness after a long-haul flight, I would strongly recommend calling 999 now or going to A&E by ambulance.

Please don't drive yourself or wait to see if it improves. A pulmonary embolism can occur days or even weeks after flying.

Can I ask you 5 important questions?

These may help me understand what's happening, but please don't delay getting medical help to answer them.

1. How does the breathlessness feel?

• Do you feel you can't get a full breath?
• Are you gasping for air?
• Does it happen even when sitting still?

2. Did it come on suddenly, or has it gradually got worse?

3. Do you have any chest pain, particularly when taking a deep breath?

4. Have you noticed any swelling or pain in either leg, particularly one calf?

5. Do you have a racing heartbeat, dizziness, faintness or coughing?

One important thing: Even if you have no chest pain and your legs look completely normal, you can still have a pulmonary embolism.

I don't want to frighten you, but I do want you to take this seriously. Sudden breathlessness following a long-haul flight is not something to watch and wait on. ❤️

Sudden difficulty catching your breath after a long-haul flight from Australia is something you need to take seriously. Please seek emergency medical attention now.

One important possibility that doctors need to rule out is a pulmonary embolism (PE) — a blood clot that travels to the lungs.

Long-haul flights increase the risk of blood clots because sitting still for many hours can slow blood circulation in the legs. A clot can develop during the flight or even days or weeks afterwards.

A pulmonary embolism can be life-threatening and needs urgent treatment.

Other possible causes

There are other explanations, including:

• Pneumonia or a chest infection – particularly if you have a cough or fever.
• COVID-19 or another respiratory virus – infections can cause breathlessness.
• Asthma or bronchospasm – narrowing of the airways.
• Heart problems – some heart conditions can cause sudden breathlessness.
• Anxiety or panic attacks – can cause a sensation of not getting enough air, but this should not be assumed until serious causes are excluded.

Warning signs of a blood clot

Look out for:

• Sharp chest pain, particularly when breathing in.
• A racing heartbeat.
• Dizziness or faintness.
• Coughing up blood.
• Pain, tenderness or swelling in one calf.

You don't need to have any of these additional symptoms to have a pulmonary embolism. www.nhs.ukwww.nhs.uk

What I would like to know

Please answer these questions if you can, but don't delay getting medical help to do so.

1. Is it difficult to get a full, satisfying breath, even when sitting still?
2. Do you have any chest pain or tightness?
3. Are you experiencing a racing heartbeat?
4. Do you have pain or swelling in either leg?
5. Did the breathlessness start suddenly today, or has it gradually developed since returning from Australia?

Most importantly: Because you're describing sudden breathlessness after a long-haul flight, please call 999 now if you're in the UK. Don't drive yourself to hospital.

I don't want to alarm you unnecessarily, but I really don't want you to overlook a potentially serious blood clot. ❤️

I'm concerned about this, particularly because you've recently taken a long-haul flight from Australia.

Sudden breathlessness after a long flight can be a warning sign of a pulmonary embolism (PE) — a blood clot that travels to the lungs. This is something that needs to be ruled out urgently.

What could be causing it?

There are several possibilities:

1. Pulmonary embolism (blood clot in the lung) – Long periods of sitting during flights increase the risk of blood clots forming in the legs. If a clot travels to the lungs, it can cause sudden breathlessness, chest pain, a racing heartbeat or dizziness. It can happen days or even weeks after flying.

2. Deep vein thrombosis (DVT) – A blood clot in the leg, which can cause swelling, pain, warmth or redness, usually in one leg. Sometimes there are no obvious leg symptoms.

3. Chest infection or pneumonia – Can cause breathlessness, coughing, fever and chest discomfort.

4. Heart-related problems – Certain heart conditions can cause sudden difficulty breathing.

5. Anxiety or panic attack – Can cause a feeling of not getting enough air, but it's important not to assume this is the cause.

(Please seek emergency medical help now)

Because you've developed sudden difficulty breathing after a long-haul flight, you need urgent assessment to rule out a pulmonary embolism.

If you're in the UK, call 999 now. Do not drive yourself to hospital. Sit and rest while waiting for help.

Can I ask you 5 important questions?

These can help me understand what you're experiencing, but please don't delay seeking emergency help to answer them.

1. How does the breathlessness feel?

• You can't get a full breath in.
• You're breathless even when sitting still.
• You feel like you're suffocating or gasping.
• You get out of breath just walking a few steps.

2. Did it come on suddenly, or has it gradually got worse?

3. Do you have any chest pain, tightness or pain when taking a deep breath?

4. Have you noticed any swelling or pain in either leg, particularly one calf?

5. Do you have a racing heartbeat, dizziness, coughing or coughing up blood?

One thing I really want to emphasise: a pulmonary embolism can occur without leg pain, without coughing and even without chest pain. Sudden breathlessness after a long-haul flight should never be ignored.

I don't want to alarm you unnecessarily, but I do want you to be safe. ❤️