I am a British-EU dual national, will I be able to use an EHIC card when I visit other EU countries?
It depends on whether you exercised treaty rights before naturalising to become British. If you have, then you and your family members (of any nationality including British), will be entitled to use an EHIC card since you are covered by the Withdrawal Agreement.
If you did not exercise treaty rights before naturalising to become British, you will still be able to use your existing EHIC card until it expires - after which you can apply for a GHIC (Global Health Insurance Card).
For more details, and to apply for an EHIC or GHIC, see here.
If you are traveling, and you need treatment but have been unable to obtain an EHIC or GHIC card, you can contact Overseas Healthcare Services.
The Government has published staff guidance which gives helpful examples of EHIC entitlement.