Liz, it's a gel nasal spray. It attacks the cold germs where they first start - in your nose. It stings a wee bit - but not a lot - and after a few minutes your nose will stream (which is quite normal). It is expensive (about £6.99) but you don't use a lot in any one go. Only a couple of squirts in each nostril.
If you Google for it, you will find a lot about it including user reviews.
I haven't got a cold... but I'm expecting to get one shortly.... well, a cold or worse!!
On the plane home from Spain yesterday I sat next to a lady and her husband who were coughing for almost the entire duration of the flight.
From what I have heard, planes are the worst places you can be for catching germs, owing to the air conditioning. A friend of mine used to be off sick from work immediately after a holiday which entailed air travel.