If illness or injury stops you travelling, your insurer will want a dated letter from a licensed doctor confirming you were unfit to fly and why. A doctor on Mobi Doctor can assess you over video, usually within 15 minutes, from home or from your hotel abroad; €57 + €10 for the certificate, where clinically appropriate.
A not-fit-to-fly letter (unfit-to-fly certificate) is a doctor's written confirmation that you were medically unable to travel on the dates you had booked. Insurers ask for it to support a cancellation, curtailment or unable-to-fly-home claim; airlines occasionally ask for it before rebooking on medical grounds. It must come from a licensed doctor who assessed you, be dated, name the condition and the dates affected, and match the claim. On Mobi Doctor an EU-licensed doctor can assess you over video wherever you are in the EU.
Unfit-to-fly certificate, medical certificate for a travel insurance claim, doctor's letter to cancel a holiday: the names vary, the content does not, and it has to fit the claim. Cancellation means you never left. Curtailment means you cut the trip short, usually to come home for treatment. Unable to fly home means you are abroad on the return date and a doctor says you should not board. Each has its own dates, and the letter must name them, matching the booking exactly.
| Claim | What happened | The letter must state |
|---|---|---|
| Cancellation | Too ill to travel before departure | Diagnosis or symptoms, date seen, departure inadvisable |
| Curtailment | Came home early through illness | Why continuing was inadvisable, date advised to return |
| Unable to fly home | Could not take the booked return | Return flight unsafe, and when to be reviewed |
Five things. The date of the assessment against the date of travel: a consultation the day before departure carries more weight than one a week after it. The clinical basis: a diagnosis, or a clear description of symptoms and findings, rather than the bare words "unfit to fly". An identifiable licensed doctor: name, registration number, contact details and a verifiable signature. Consistency with the claim: a letter about 12 September 2026 does not support a claim about travel on 10 September. And the policy wording: undeclared pre-existing conditions, pregnancy cut-offs (the RCOG advises a policy that lets you cancel for pregnancy reasons) and the definition of "medical practitioner" differ by insurer.
As close to the affected date as you can, and ideally before you cancel anything. The doctor can record what you report about earlier days ("seen on 24 September 2026; reports fever and vomiting since 21 September") but cannot certify a state of health that was never assessed. A retrospective letter is therefore documented history rather than a contemporaneous finding, and insurers treat it as weaker evidence. If you are unwell and hoping to recover in time, being seen now creates the record you may need later.
A letter issued through Mobi Doctor for an insurance claim states:
When there is no clinical basis. A doctor will not certify unfitness for a condition that does not stop you flying, for symptoms that had resolved before you were seen, or to cover a non-medical reason for cancelling. Nor will the doctor alter dates or add a diagnosis that was not made. What you get instead is an honest assessment: if you are fit, a fit-to-fly certificate where clinically appropriate; if a condition needs treatment, advice and, where appropriate, a prescription sent to a pharmacy you choose. Either way it is a full consultation, not a document service.
The UK CAA's guidance is explicit: the final decision on carrying a passenger rests with the airline, anyone with a contagious illness should delay the flight until it has passed, and an active or contagious infection bars travel until it is under documented control. Visible illness, a fresh plaster cast (see flying after surgery) and a pregnancy past the carrier's cut-off (see flying while pregnant) are the usual triggers; the fit-to-fly guide lists the rest. If it happens, get written confirmation of the refusal before you leave the airport, then see a doctor so the medical side is documented independently. Airlines generally do not refund for illness; travel insurance does, and the refusal note plus the doctor's letter are the two documents a claim needs.
Policies typically ask for a certificate from a licensed medical practitioner who assessed you, usually without saying how. A letter issued through Mobi Doctor names an EU-registered doctor with registration number and contact details, records that the assessment was by video and gives the clinical reason.
No. It carries the date of the consultation. The doctor can record the history you give, including when symptoms began, but cannot certify a date on which you were not assessed.
Possibly, with weaker evidence. A doctor can document your account and any records you have (receipts, an out-of-hours note, airline messages) and give an opinion on whether the illness described would have made travel inadvisable; the insurer decides its weight.
Call your insurer's assistance line first; many policies require it for curtailment and extended stays. Then get the medical position documented: a doctor on Mobi Doctor can assess you over video from your hotel, usually within 15 minutes. In an emergency call 112.
Then you get that in writing instead, as a fit-to-fly certificate where clinically appropriate, with advice or treatment for whatever prompted the consultation. A doctor cannot issue an unfit-to-fly letter without a clinical basis, and an insurer would not accept one.
Generally not. A non-refundable fare stays non-refundable; some carriers may rebook you with a medical certificate, at their discretion. Loss caused by illness is what travel insurance is for, which is why the letter is written for the insurer.
Your booking with its dates, any hospital or pharmacy paperwork, a list of your medicines, your policy number and the claim type you intend to make. For curtailment or unable-to-fly-home claims, also the original return date.
€57 for the video consultation plus €10 for the certificate. The €57 is a full consultation, so treatment advice and, where appropriate, a prescription for the illness itself are included. Check whether your policy covers the cost of a medical certificate.
General information, not medical advice — always confirm with your insurer before you travel.
