Travelling with Medicines
You will be able to be able to carry essential medicines through customs. They will need to be placed in a clear, plastic, re-sealable bag and in containers of 100ml or less, please do bear in mind that this information could be subject to change in regulation.
Any essential medicines that are of more than 100ml will only be allowed through customs with the correct supporting documents from a relevant qualified medical professional and through prior arranged approval from the airline. This is applicable to everything of over 100ml whether it be medicine or insulin. There is a chance they you may also be required to verify the medicines through taste or testing on the skin.
Please remember that you can keep spare containers in your hold baggage and make sure you take enough to last you for the entire length of your holiday, taking into account the potential for delays and unexpected events at either end. More information is available from the Air Travel FAQs at the Department for Transport website.