Echinocactus grusonii
If you are a fan of cacti and have the odd specimen, when handling them you will have to be very careful, since its thorns can cause you a lot of damage. Sometimes they even get embedded in the skin, causing pain and discomfort.
How to remove thorns from cactus? Very simple. Just follow the advice I will offer you below, and you will see that you will not have to worry - at least not too much - about this issue again. 
How to remove a thorn from a finger or from another part of the body?
You are calmly extracting your cactus from the pot or watering, and you do not realize it and a thorn remains stuck in your finger. What to do in these cases? Well, the first thing is to try to stay calm and go for some tweezers if it is long or for adhesive tape (tape) if it is small.
Once you have it, simply you have to take the thorn with the tweezers and pull it out; Or wrap duct tape on your opposite hand and pass it over where it got stuck. In the event that the spine has been broken and / or has remained completely inside the skin, I advise taking a sterile needle or previously disinfected with pharmacy alcohol and poking a little until it is removed.
How to remove skewers from clothes easily and quickly?
When you pass near cacti like those of the Opuntia genus, you have to know that you run a serious risk of ending up with more than one thorn or skewer in your clothes. When that happens, you never have to try to remove them by hand, since if you do, those thorns will dig into your skin.
Knowing this, what I advise you is that take a hair remover roll and run it through your clothes. These types of rolls can cost you less than 1 euro in any bazaar, and they are very useful both for what they were designed and to remove thorns from clothing that may have become encrusted.
What to do if my wound gets infected?
Sometimes if the thorn is stuck inside, clean tools have not been used, or the needle has been poking too hard, the wound can become infected. What happens in these cases? Well what an abscess forms - accumulation of pus-, which is quite painful.
Generally, it will heal on its own after a few days, but if you notice a lot of discomfort, do not hesitate to go to the doctor, who will prescribe antibiotics.
Are there cacti with poisonous spines?
The truth is that no. The thorns by themselves are already an excellent weapon to protect them from predatory animals, so they do not need to also have venom to scare them away. But they can be irritating., so especially if you are a beginner (with time you get used to it  ) it is very important that you wear gloves when handling your plants and that you wrap them in newspaper if they have very short or, on the contrary, very long thorns.
Opuntia microdasys
If you have doubts, do not leave them in the inkwell.