I have had a piece of rusty staple in my wrist for, let’s see…51 years now. (I was jumping up to remove a poster from a wood utility pole)
It caused me some pain at the time, but never since. I can see it under my skin still.
CW
Ignoring injuries caused by embedded thorns or other foreign bodies until you think they’ve gotten infected is a recipe for trouble. One risk is that of osteomyelitis (bone infection), definitely Not A Good Thing. Plantar foot injuries for example can cause it.
Opportunistic pathogens can be introduced into such wounds. Those working around roses can develop sporotrichosis (a fungal infection) from thorn impalements. Usually it’s confined to the skin and the hazard is a non-healing ulcer. A rarer consequence in the susceptible is disseminated sporotrichosis, another Very Bad Thing.
That must be pretty common. I got a bit of pencil lead into my hand back in grade school. I could see it there for many years afterwards; I suppose I could feel it right after it happened, but for years it was just something I could see, no other symptoms. Eventually it disappeared, but I don’t remember when – I think it was gone by the time I was 40, but it might have been sooner or later. It didn’t come out, it just gradually faded from sight.
I get solanacea thorns in my hands sometimes harvesting eggplant. (Some varieties are thornier than others.) Generally those form that bit of pus and move out, often with some help from a sterilized needle.
I have a friend who’s 50 now and when asked if he has any tattoos, always shows you a small blue spot on his hand where he was once stabbed with the tip of a ball-point pen by a schoolmate that never went away.
I had a thorn stuck in my finger a couple of years ago. It was very small almost hairlike. I couldn’t get it out and gave up. That night I was awoken by a horrible throbbing in my finger. I wrapped it in a wet, hot washcloth. The pain was unbelievable and my finger was swollen. I could barely sleep the rest of the night. I went to urgent care on my way to work. It turned out to be cellulitis. I was given a prescription - I don’t remember what. It was fine within a day. I most likely infected it by digging around trying to get it out. The doctor told me that as long as it was from a plant and not metal it would just dissolve. And it did.
Soaking in hot water can help work the thing to the surface, but it also helps your immune cells get to the object, where they will surround it with puss and “eat” it. This is a healthy, local response, and helps prevent a bad response. What you don’t want is an infection that gets into the blood or other tissues.
btw, welcome to the SDMB !
(see what you’ve started ?!)
I have a stereo microscope that I use to assemble/rework circuit boards. I’ve found that it’s also a great tool for finding and removing even the tiniest splinter.