How can I heal this thing without poisoning myself?

I would have it looked at by a doctor. Cold sores are very common and not difficult to transmit.

Either way, try some vaseline/petroleum jelly. It won’t “heal” the wound, but it will keep the area moist and supple so that it won’t crack further when you move your mouth, and it will protect while it heals naturally.

Well, you seem to have a cold sore now. It will eventually resolve itself but you might try something like Carmex to ease the irritation.

Is it that the skin at the corner of your mouth is cracked? Or is it a sore?

It doesn’t seem like a sore, but it’s a little more than just cracked.

Okay.. I’m not too sure by your description, but if it’s a cracking at the corner, I get that every now and then and it’s super annoying because it’s difficult to heal. I’ve read that a possible cause is a vitamin/nutrient deficiency. I imagine if you picked at it or it kept opening it would get worse than a simple split. Mine usually go from being a split to being inflamed and sore, but I never pick at them and try to keep the spot coated with a beeswax-based lip balm. This helps keep moisture in and painful, stingy stuff out. And then the only other thing is to not touch it with my tongue (though it’s tempting) and try not to open my mouth too wide until it heals.

Thank you, @MissAnthrope! Sounds exactly right. I will do all that.

Welcome! Hope it heals quickly.. I think eating dark leafy greens and stocking up on vitamin C is supposed to help healing. Also, you want a beeswax-based product rather than a petroleum-based one to avoid ingesting nasty stuff. Petroleum/petrolatum salves and such are great for dry skin elsewhere, though.

Carmax or a similar product with salycylic acid (not sure of spelling) will soften the scab and allow you to open your mouth, etc without it popping open. Heals it up nicely.

I get them from time to time. They drive me fucking nuts and then all of a sudden one day i wake up and its completely gone lol. I didnt think they were cold sores though…

Don’t worry – it’s not a cold sore.. it’s totally different. It’s simply cracking at the corners of the mouth.

16. Do you have cracking or open sores in the corners of your mouth?
...........Yes—>
...........These tender sores may result from a vitamin deficiency or from chapped lips.—>
...........Use a soothing ointment on these cracked areas. Take riboflavin and/or a multivitamin if you think your diet isn’t adequate. See your doctor if your symptoms don’t improve. (link)

Sounds like angular chelitis which is realllly annoying. Like the wise Jellies above me said, it can be from a vitamin deficiency. I’ve also know it to come about if I am congested and have to sleep with my mouth open. If that’s the cause, I have a weird but effective recipe for you to use. And oddly, Vaseline etc is NOT effective for this.

@MissAnthrope ahh cool thats what I thought cause I always get them from chapped lips.

It does indeed sound like angular cheilitis as mentioned above. I often find that putting triple antibiotic cream ± clotrimazole (both over the counter) can speed up the healing process, since the area can frequently become infected. If the problem is persistent, you should see a doctor for a thorough evaluation.

L-Lysine in cream form helps a lot.
Perhaps see your dentist.
Those corner cracks can be caused if your mouth closes to far
(from teeth being worn down). The corner folds of the skin lie on one another where normally they don’t. A slight yeast infection can follow creating the crack. Acidophilus in pill form helps at times. Yogurt that has the live bacillus is good also.