@Alexandra100 , a simple thing which is sometimes overlooked is preparing the arm properly before applying. I'll always shower or wash my arm to remove residual grease, use the alcohol wipes, and also shave the application area during the washing.
Heavens forfend, I'm not suggesting for a second you've got hairy arms, but most people, if they look closely, will find that they've got some hairs or a fine peach-fuzz, and that stuff can really compromise stickiness to a surprising degree if it's left to grow for 2 weeks under the sensor.
So, definitely think about running a razor over the arm first.
Most chemists sell Molnlycke Mepore 7 by 8 cm plasters for about 20p. They're not the classiest looking thing on the planet, but I always pop one on top because it smooths out the edges and makes it less likely to snag.
Some of the falling off episodes we read about are not so much to do with the inherent stickiness, more to do with just getting used to the fact that there's something on your arm, so avoid knocking it. I lost my second or third one, because I didn't realise how often I edged door-jambs. And paying attention to things like taking off rucksacks, jackets etc.
Am on my 54th at the moment and have only had 1 fall off, and that was because of bumping a door-jamb.
Tegaderm seems to be a good bet for swimmers.
