Do you need to declare an undiagnosed condition for travel insurance?

Around 16 million adults in the UK don’t realise that failing to declare an undiagnosed medical condition could invalidate their travel insurance, according to new research from Co-op Insurance.

Long waits for assessments and more people stuck in ‘diagnostic limbo’ mean some travellers are unsure about what they must disclose when buying a policy.

Here, Which? explains when an undiagnosed condition needs to be declared, how this affects your cover, and what to do if you’re struggling to find an insurer who'll cover you.

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What is an undiagnosed medical condition?

Insurers class an undiagnosed condition as any health issue that's being investigated but doesn't yet have a confirmed diagnosis. This can include:

• symptoms you’ve spoken to a GP about
• referrals for tests or scans
• ongoing investigations for physical or mental health concerns
• waiting lists for assessments, such as ADHD or autism
• suspected conditions your doctor is monitoring.

Find out more: best travel insurance companies and policies

Can it invalidate your cover?

Yes. If you buy travel insurance without declaring a health issue that's still being investigated, your policy could be treated as invalid.

Insurers expect you to disclose any symptoms, referrals or tests that are underway, even if you don't yet have a diagnosis.

If you make a claim and the insurer later discovers you were waiting for medical investigations, it may refuse to pay out. This can apply even if the claim is unrelated, leaving you to cover costs yourself.

If you're unsure whether to declare something, check with your insurer before you travel. It's always better to ask than risk a rejected claim.

• Find out more: best travel insurance for over-65s

Why do travellers get caught out?

People often assume they only need to report confirmed illnesses, not symptoms or assessments that are still in progress.

The issue is widespread. According to Co-op Insurance, around 21% of travellers have an undiagnosed condition, with many waiting for assessments for ADHD or autism, or tests for concerns such as cancer or epilepsy. As a result, more people are booking trips while their health status is still uncertain.

There is also confusion about whether an undiagnosed condition matters if it feels unrelated to the trip. Insurers still need to know about it, which means many travellers may not realise their cover could be at risk.

Getting cover if you have health concerns

If you have a diagnosed condition or you're still waiting for tests or assessments, you may need to look beyond standard travel insurance policies. 

Many insurers will ask extra screening questions or may not offer cover at all if your health status is uncertain.

Here are the steps worth taking:

1. Use a specialist medical travel insurer Some insurers focus on covering travellers with complex or ongoing health issues. They carry out detailed medical screenings, which can help you find a policy that better matches your situation.
2. Call before you buy If you're unsure how to declare your symptoms or referral, speak to the insurer directly. They can tell you what information they need and whether they can offer cover.
3. Check policy exclusions If you have an undiagnosed condition, some policies may offer cover but exclude claims linked to that specific issue. Make sure you understand what is and is not included before you travel.
4. Compare policies carefully Premiums can vary widely depending on your medical history, so it's worth comparing options from multiple providers.

For more help finding the right provider, see the best travel insurance for people with medical conditions.