Top tips for travelling with underactive thyroid

Your thyroid gland punches well above its weight, given its small size. About the size and shape of a bow tie, it sits at the front of your neck and produces two main hormones – thyroxine and T3 – that instruct your body's metabolism on how fast to tick over. Hormones are chemicals made in one part of the body that travel in the bloodstream to another part to have their effect.

Between 1 in 50 and 1 in 100 people develop an underactive thyroid, mostly developing in adulthood, and getting more common as you get older. Like an overactive thyroid, it affects ten times more women than men, occurring when your body doesn't produce enough thyroxine, slowing your metabolism as a result. This can lead to weight gain despite symptoms such as reduced appetite as well as: tiredness; feeling the cold; constipation; dry skin and coarse hair; aching; mental slowness and depression.

Treatment for an underactive thyroid involves daily thyroxine tablets for life. It can take a little trial and error to find the right dose and your response will be checked with regular blood tests. Once your levels are stable, you can usually keep taking the same dose with an annual check.

My top tops when travelling

If you have underactive thyroid:

• Keep your medicine in its original packaging, complete with your name and other details.
• Order your medication well in advance and take enough to last the whole trip, with a spare supply in case you get stranded. Pack it in your hand luggage and ideally, split your supply between you and someone else you're travelling with, just in case your bag goes astray. However, do make sure you go through security with them – it will be your name, not theirs, on the packaging.
• Take a copy of your repeat prescription with you in case it's checked at airport security. This can also be useful if you lose your medication while you're away. In some countries, it's possible to get a repeat supply of medication from a pharmacist without a doctor's prescription, but they will definitely need to know the name and dose of your medicine.
• If you're due for a blood test to check your levels of thyroxine, make sure you get them done before you go. Ideally, make your appointment a few weeks before departure so that any changes in dosage can be implemented. If your dose of thyroxine is changed, your doctor will usually want another blood test about 6 weeks later.
• Work out a schedule to ensure you take your medication at regular intervals. This is more of an issue if you're crossing time zones. If you can, you want your timing to be as close to your usual home schedule as possible.
• An underactive thyroid can lead to you tiring easily, especially if your thyroxine levels aren't completely stable. Factor this in when booking your holiday – if the activities are too energetic, you may not be able to take part or fully enjoy yourself.
• An underactive thyroid can also make you feel the cold more. If this applies to you, think about where you're going - a trip to Greenland might not be a good plan! Do also bear in mind that even if you're going to a warm country, planes are air-conditioned and often quite chilly. Ideally, dress in several layers rather than one thick jumper – this allows you to take layers on and off as you feel warmer or colder.
• Having an underactive thyroid can also make your skin dry, leaving you prone to a dry throat. Make sure you keep well hydrated – this is particularly important if you're visiting a very hot country, or when your travelling in a plane (the air on planes is often very dry).
• Even if you're travelling to Europe and have a valid EHIC or GHIC, it's essential to take out the correct travel insurance. Always declare your condition to your travel insurance providers and look for a specialist provider who will cover your condition.