Toddlers are snotty, disgusting little creatures who are prone to just rubbing their running noses across whatever is handy when the need arises. The only way you can try to prevent this level of gross is to learn how to teach your toddler to blow their nose with some level of success. It won't completely eliminate their inclination to drag their nose across their sleeve like a drunken snail slimily scooting over the terrain, but it may decrease the frequency with which they do it.
One of the best educators to show you how to teach your toddler to blow their nose are occupational therapists. Teaching kids how to control their bodies is quite literally their job, and they are really good at it. Dr. Chaye Lamm Warburg, DPS, OTR, founder of Pediatric Occupational Therapy Services, LLC, tells Romper that a big part of teaching your child to blow their nose is using a child's sensory resources to your advantage. When you engage sensory input, she explains, that it makes it fun. She suggests starting by "placing a mirror under your toddler's nose, so when he/she breathes out it will steam up," showing them how their nose is working. You can also try teaching them to plug a nostril (and close their mouths) and use the air expelled to push light objects like pom poms across the surface of the mirror. You can even put a cotton ball inside of a toilet paper tube and encourage them to try to push the ball out with the air from their nose.
That is, of course, not the only way to teach a child to blow their nose. It's a fun way, and a messy way (meaning kids will absolutely love it), but if it grosses you out, there are alternatives.
"The problem, of course, is that many toddlers either suck in through their noses when they try to blow, or they blow out through their mouths," pediatrician Steve Silvestro, M.D./FAAP and host of The Child Repair Guide Podcast, tells Romper. Or, like my son, they try to blow it out of all of their holes, and end up filling their diapers. (I bet you didn't know that can happen.)
Silvestro says that "the trick is to hold a tissue an inch or two away from the child’s face, then ask them to make it move by blowing with their mouth." After that, he says that you should "ask them to make it move by blowing with their nose." This begins the sequence needed for a successful technique, Silvestro notes, because once they master that first step, they can "then put the tissue onto their face over their nose and ask them to make it move with their nose again. The result is that she will effectively blow her nose into the tissue."
Personally, I suggest doing this while they're in the bathroom, for obvious reasons. Not the tub, as again, all that blowing can lead to unexpected results for all parties involved.
Dr. Chaye Lamm Warburg, DPS, OTR, founder of Pediatric Occupational Therapy Services, LLC
Steve Silvestro, M.D./FAAP, host of The Child Repair Guide Podcast