If you're heading overseas this year it's vital that you make sure your travel insurance is in place. Heading abroad without it can leave you thousands of pounds out of pocket if you need urgent medical treatment or your belongings are lost or stolen while you are away.

Even if you have arranged travel insurance it is not guaranteed that you will get a payout if you have to make a claim. There are lots of things that can invalidate your cover, and now a leading comparison website has put together a list of things that could lead to your travel insurance claim being rejected.

Keep reading for our list of five things that could put your travel insurance claim at risk.

1. Not covering yourself for sport activities 

If you plan to undertake any dangerous sporting activities while on your holiday you are advised to take out specialist cover.

For example, a traditional travel insurance policy won't generally cover you for quad biking, bungee jumping, skiing, paragliding or rugby. If you are planning to engage in dangerous sports or activities make sure these are covered under your policy.

2. Travelling to a dangerous destination

Your cover may also be at risk if you are planning to travel to a dangerous or volatile destination. This is generally somewhere that the Foreign & Commonwealth Office (FCO) or the World Health Organisation has advised you to avoid.

For example, countries that the FCO currently says Brits should avoid include Syria, South Sudan, the occupied Palestinian territories and Lebanon.

In addition, you should always make sure you have the right paperwork and documentation when travelling overseas. Ensure you arrange visas or any other official documentation for the countries you plan to visit as if you don't your travel insurance may not pay out.

3. Not declaring pre-existing medical conditions

The cost of your travel insurance will partly be determined by how likely the insurer thinks you are to make a claim. If you have any pre-existing medical conditions then these will be taken into account during the underwriting process and they may affect the price of your cover.

It is therefore important that you declare any condition - however minor - at the outset. It may add a few pounds to the cost of your policy but if you don't declare it the chances are that your insurance claim will be invalidated.

4. Travelling against medical advice

If you don't declare pre-existing medical conditions to your insurer then your policy may not pay out when you make a claim. However, even if you have declared a condition you may still invalidate your cover if you don't take prescribed medication or you travel against medical advice.

This also includes not getting the recommended inoculations for the country you are visiting.

5. Behaving recklessly

If you put yourself at unnecessary risk while on your holiday your insurer may refuse a claim. Examples include:

  • Not taking reasonable precautions to avoid injury or illness
  • Drinking too much
  • Acting recklessly - for example sitting on a balcony railing, jumping from a great height into water
  • Using a swimming pool outside authorised hours
  • Not taking precautions to protect your property against theft or loss