Travelling with medicines: carrying, controlled drug letters and time zones

TravelHealthPro, the UK public-health travel resource, suggests a medical check-up well in advance to talk about fitness to travel and to make sure supplies will last. It adds that the NHS typically covers medicines for trips of up to three months abroad, which means a long stay needs a different plan, for example arranging care at the destination.

Ask your pharmacist for medicines in original, labelled packs rather than dossette boxes, as border staff and airlines can only recognise a medicine in its packaging.

The common advice is to take everything you need in hand luggage so a lost suitcase does not leave you without treatment, and to keep a second small supply in the hold. Check airline rules on liquids and on carrying needles, pumps and sensors, and ask your clinic for a letter if you use injectable or device-based therapy.

• Original packaging with your name, the generic drug name and the dose visible.

• A printed list or repeat-prescription copy, using generic names rather than brands.

• A letter from the prescriber listing the medicines, doses and the condition treated.

• A cool bag or approved device where the medicine needs temperature control.

• Travel insurance that covers existing conditions.

Some prescribed medicines are controlled drugs under UK law. TravelHealthPro names diamorphine, diazepam, codeine, fentanyl, methadone, morphine, pethidine, methylphenidate and temazepam among those to check. GOV.UK says you must carry medicine containing controlled drugs in your hand luggage, confirm with your doctor or pharmacist whether yours is one, and be able to prove it is prescribed to you with a prescription or a doctor's letter.

A personal licence is generally not needed for routine travel. For exceptional circumstances, such as more than the standard three-month supply, GOV.UK says you may be able to apply to the Home Office's Drug and Firearms Licensing Unit, and TravelHealthPro advises applying at least 10 days before travel if carrying three months' supply or more. Without the right paperwork, medicines can be confiscated. Medical cannabis and CBD products have varying legality, and some countries apply zero-tolerance rules.

GOV.UK advises checking the regulations of the country you are visiting through its embassy, and TravelHealthPro points to Foreign, Commonwealth and Development Office country advice. This matters most for opioids, benzodiazepines, ADHD stimulants and some sleep or anxiety medicines.

GOV.UK also covers people arriving in the UK: non-residents carrying controlled drugs need a letter of proof of prescription, and Schedule 1 drugs cannot be brought in without a licence.

The sources above do not give a one-size schedule for crossing time zones, and nor can a general page. The principle clinicians use is that the dosing interval matters more for some medicines than for others. A once-daily tablet with a wide safety margin can be shifted by a few hours without trouble, whereas insulin, anticoagulants, anti-epileptic drugs, Parkinson's medicines and some contraceptives are more time-sensitive.

If you take any of these, ask your prescriber or pharmacist for a written plan before you fly, including whether to keep home time for a day or two and then change gradually. Set phone alarms in both time zones, and keep the plan with the medicines. For jet lag more generally, an existing page covers the condition.

Appearance and composition of a medicine can differ between countries, and brand names vary. If you need extra supplies, TravelHealthPro advises seeking a pharmacy or healthcare provider for advice and avoiding buying medicines abroad where possible, given counterfeit and substandard products.

On return, TravelHealthPro suggests seeing your doctor if you started any new medicine while away. Keep receipts and packaging until then.