Are you on regular medication or do you add any to your routine when flying? You might want to take a closer look at your travel kit.
You’ve waited months for this holiday. Packing’s done, transfers are booked — the prep has practically taken over your life. You’ve got the noise-cancelling headphones, the under-eye masks for optimal in-flight skincare (the stares are worth it) and you’ve even pre-downloaded your favourite series.
But there’s one thing you may have overlooked: your medication.
Doctors are warning that some everyday meds can interact unpredictably with the flying environment — and should be approached with care or even avoided.
GP and Women’s Health Specialist Dr Deepali Misra-Sharp explains: “Air travel places the body under unique physiological stress — cabin pressure, reduced oxygen availability, low humidity, immobility and disruption to circadian rhythms.”
These factors can interact with medications in ways that amplify side effects or lead to unexpected complications. Medichecks Digital Clinician Dr Susanna Hayter adds that the longer the flight, the more significant the risk.
No one wants to feel unwell on a flight — especially if it can be prevented. So, which medications are worth flagging beforehand?
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1. Opioid painkillers (e.g. codeine, tramadol, morphine)
If you’re prescribed opioids, it’s likely for good reason — and hopefully with clear instructions. But flying changes how your body reacts.
“Cabin oxygen levels are equivalent to being at 6,000-8,000 feet,” says Dr Misra-Sharp. “In healthy people, this usually causes no issue, but opioids increase the risk of hypoventilation, reduced oxygen saturation and in rare cases, type 2 respiratory failure.”
This is the worst scenario, of course, but they can also worsen flight-related issues, such as bloating or nausea due to slowed digestion.
The advice? Unless absolutely necessary and prescribed, avoid taking opioids while flying — no reason to add to the discomfort or risk.
2. Sleeping pills (e.g. zopiclone, temazepam)
They may seem like the dream ticket to a stress-free flight, especially if you hate flying. But sedatives can dull your senses and delay reaction times — not ideal in the (very rare) case of an emergency.
“Sedative-hypnotics suppress the central nervous system,” says Dr Misra-Sharp. “While they help with sleep, they also reduce calf muscle activity, which is vital for preventing deep vein thrombosis (DVT) on longer flights.”
Plus, because of how these drugs redistribute in the body at altitude, their effects can linger well beyond landing. Cue grogginess, balance issues or even confusion that might even make you forget your things on the plane.
3. Anti-anxiety medications (benzodiazepines, e.g. diazepam, lorazepam)
Benzodiazepines work by calming the nervous system — but they also reduce respiratory function and coordination, especially in low-oxygen environments, such as a plane.
Worse still, says Dr Misra-Sharp, many passengers combine them with alcohol, which can “cause severe drowsiness, confusion or paradoxical agitation (i.e. unexpected restlessness or aggression)”.
Older passengers are particularly at risk. With longer half-lives, these drugs can linger in the system, potentially leading to delirium or memory problems post-flight.
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4. Diuretics (e.g. furosemide, bendroflumethiazide)
Prescribed for high blood pressure or fluid retention, diuretics increase urine production — not exactly ideal on a cramped plane.
They can also cause dehydration, electrolyte imbalance and dizziness, all of which are worsened by the dry cabin air. “Low humidity and immobility can amplify side effects, such as muscle cramps or even fainting,” says Dr Misra-Sharp.
And let’s be honest — needing to rush to the loo every 20 minutes mid-flight is neither fun for you nor your seat row.
Plus, as Dr Hayter says they can “cause a dry mouth and lead to a sore throat”, and the last thing you need if you’re struggling with diuretics on a flight is another reason to drink more water.
5. Drowsy antihistamines (e.g. diphenhydramine, chlorphenamine)
They’re over the counter and seem harmless enough, but ‘first-generation’ (developed in the 1940s) antihistamines can cause unexpected sedation and anticholinergic side effects, such as dry mouth, blurred vision or confusion.
“In older adults, there’s a small risk of acute delirium,” says Dr Misra-Sharp. “And in rare cases, children may experience paradoxical stimulation — restlessness, even hallucinations.”
If you’ve never taken one before, a flight might not be the best time to try.
Dr Hayter’s advice: “Go for a safe, non-sedating alternatives, such as cetirizine or fexofenadine.”
6. Muscle relaxants (e.g. baclofen, tizanidine)
These can ease chronic pain or muscle spasms, but they also lower blood pressure and cause drowsiness.
“Add that to long periods of sitting and low mobility, and there’s a real risk of dizziness or even falls,” says Dr Misra-Sharp. Urinary retention is another possible side effect, she says, particularly if you’re also on antidepressants or allergy meds.
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7. Blood thinners (e.g. warfarin, apixaban, rivaroxaban)
These aren’t unsafe to take on a flight — but they do need careful management.
Dr Misra-Sharp explains: “Changes in eating or sleep patterns can affect warfarin control, and direct oral anticoagulants (DOACs) must be taken consistently to avoid complications.”
Minor bumps from turbulence or moving around the cabin can lead to bruising or soft tissue bleeding. Ironically, not moving enough raises your risk of clots — the very thing these meds are meant to prevent.
8. NSAIDs (e.g. ibuprofen, naproxen)
Often over-the-counter pain medications, you might not expect to have to be wary of these at all. But Dr Misra-Sharp warns of at least some risk. While effective for pain and inflammation, they can irritate the gastric mucosa, cause fluid retention and reduce renal perfusion in dehydrated states, which are all more likely during air travel.
Dr Misra-Sharp says that when taken without food (as often happens while travelling) or alcohol, the risk of gastritis or dyspepsia is higher. So just ensure you’re eating — as you’re advised anyway when taking these.
9. Insulin and hypoglycaemic agents
If you’re diabetic, flying can throw your blood sugar regulation off-track.
“Time zone changes, skipped meals and unusual activity levels all affect glucose control,” Dr Misra-Sharp warns. Sulfonylureas and rapid-acting insulin are particularly risky if taken without food leading to hypoglycaemia, which can cause dizziness, confusion or fainting.
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10. Hormones and the contraceptive pill (e.g. HRT, Oestrogel, Lenzetto, HRT patches, Rigevidon)
Anyone on the contraceptive pill or taking hormone treatments should also be wary during plane travel, warns Dr Hayter.
There’s small risk of blood clots on the contraceptive pill (around 0.3% to 1%) and on hormone replacement therapies containing oestradiol. Combined with immobility and potential dehydration on long-haul flights, this risk is increased.
But you don’t need to stop taking these for a flight. “Just consult your GP beforehand, stay hydrated, walk up and down the cabin regularly (if it’s safe to do so) and think about getting flight compression socks,” Dr Hayter advises.
11. Antipsychotics and some antidepressants (e.g. olanzapine, quetiapine, amitriptyline, pregabalin)
If you’re taking any medication like this, it’ll likely be a controlled dosage, but Dr Hayter flags that you shouldn’t change, stop or adjust these doses before flying as it can lead to drowsiness and confusion.
She adds that you can also get “orthostatic hypotension, which is where you feel dizzy on standing and may faint, which is worsened by dehydration and tiredness caused by the flight”.
And very rarely, some of these drugs can also cause problems with your heart rhythm if you’re very dehydrated.
12. Anti-sickness medications (e.g. scopolamine and motion sickness patches)
If you get travel sick, you might be wondering how else you’re supposed to fly? Especially when turbulence and ear issues are adding insult to injury.
But motion sickness patches can cause a dry mouth, blurred vision and, in elderly passengers, confusion. Dr Hayter suggests opting for travel sickness pills instead.
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How to stay safe while flying when taking medication
The takeaway? Flying alters how drugs behave in your body and even low-risk, everyday medications can act differently in the air. A little planning goes a long way toward making sure your trip is as smooth and safe as possible.
To reduce your risk of side effects or complications:
- Minimise sedating medications
- Stay hydrated and eat regularly
- Keep moving — especially on longer flights
- Carry essential meds (like insulin) in your hand luggage
- Consider buying compression socks in advance
- Speak to your GP before you travel, especially if you’re on long-term medications
- Avoid adjusting or stopping medication dosage before flying
- Opt for oral travel and motion sickness solutions over patches
- Avoid overconsuming alcohol during the flight
