Air Travel Health: Jet Lag, Dehydration and Deep Vein Thrombosis

Air travel makes long-distance journeys faster, but extended periods of sitting, changes in time zones and the dry cabin environment can leave some passengers feeling uncomfortable. Fatigue, disrupted sleep, thirst and swollen feet are common travel concerns, although their causes and severity differ.

A little preparation can help travellers manage these issues and recognise symptoms that require medical attention.

Why flying can affect your body

Jet lag and disrupted sleep

Jet lag occurs when travel across several time zones disrupts the body’s internal clock. Travellers may experience daytime sleepiness, difficulty sleeping at night, reduced concentration and digestive changes.

To adjust, gradually move your bedtime towards the destination’s time before departure when practical. After arrival, use daylight exposure and regular meals to help establish the new routine. Keep naps short if they make it harder to sleep at the appropriate local time.

Avoid relying on alcohol as a sleep aid. If you are considering melatonin or another sleep product, ask a healthcare professional whether it is appropriate for you.

Dehydration and cabin discomfort

Aircraft cabins generally have low humidity, which can contribute to dry eyes, dry skin and dryness in the nose or throat. Travellers may also drink less water than usual because of airport queues or limited access to toilets.

Drink water regularly and carry a refillable bottle where airport security rules permit. Limit excessive alcohol, which can worsen sleep disruption and may contribute to dehydration. People with medical conditions requiring fluid restrictions should follow their clinician’s advice rather than increasing fluid intake indiscriminately.

Deep vein thrombosis and prolonged sitting

Deep vein thrombosis (DVT) occurs when a blood clot forms in a deep vein, usually in the leg. Long-distance travel involving more than four hours of sitting can increase clot risk, particularly in people with additional risk factors.

These may include a previous blood clot, recent surgery, certain cancers, pregnancy or the postpartum period, and some hormone treatments. Most travellers do not develop a clot, but awareness matters.

During long journeys, move your feet and ankles regularly, change position and walk when it is safe to do so. If you have a history of blood clots or other significant risk factors, speak to your healthcare professional before travelling. Do not start aspirin or anticoagulant medication for travel prevention without medical advice.

A practical pre-flight health checklist

Pack regular prescription medicines in your hand luggage and keep them in their original packaging when practical. Check airline rules for medical equipment and liquid medicines. If you have a chronic condition, carry relevant prescriptions and medical information.

Choose comfortable clothing and plan movement breaks during long journeys. If you are prone to motion sickness, ask a pharmacist or clinician about suitable options before departure.

After arrival, prioritise daylight, appropriate hydration, regular meals and sleep according to the destination’s time zone.

When to seek medical attention

New one-sided leg swelling, unexplained leg pain, warmth or redness after travel can indicate DVT and require prompt medical assessment.

Sudden breathlessness, chest pain, coughing up blood or fainting may indicate a pulmonary embolism, a potentially life-threatening complication. Seek emergency medical care immediately.

Persistent or severe symptoms should not be dismissed as ordinary travel fatigue.

The takeaway

Healthy flying is not about eliminating every discomfort. It is about preparing for sleep disruption, staying comfortably hydrated, moving during long journeys and understanding your personal clot risk. These straightforward measures can help make travel safer and more manageable.