Another vote for magnesium sulphate!
I also highly recommend using titanium studs if you don't want to leave the holes empty. I use titanium for most of my piercings and have never had any bother. It's one of the metals that people have the least reaction to. I get all mine from "Ouch Body Jewellery" - there's loads of choice and they're good for delivery.
I left my earrings out for a few years and the holes in my lobes didn't close up at all. However, the piercings higher up my ears do start to close after a couple of weeks if I don't wear earrings, and my nose piercing closed up after only a day, despite having been pierced for three years
I had to take my nosering out for a tack & turn out class at a local show, and by the time we had gotten back, sorted the horses out and I got home and started putting my piercings back in, the piercing had sealed up so much that I just couldn't get it through. I took my labret piercing out a few months ago, because the back of the stud had started to bruise and wear down my gums (after years of wearing it hassle-free) and the inside of the lip still has a dimple that I can feel with my tongue and the outside hole is much smaller but still visibly a piercing.