Getting fiberglass out of your arm would depend totally on how it got in there in the first place. If you have been in an accident of some sort and have managed to get the shrapnel of some fiberglass into your arm, then there is a simple way of tackling the situation. It would depend upon the size of the shrapnel or splinters that have managed to penetrate the surface of your skin. If they are large enough to be seen, then it is possible to remove them by hand. You should begin with cleaning the surface of the skin with ethyl alcohol so as to not spread infection of any kind. You can then use a pair of sanitized tweezers to pull out fragments of shrapnel from your skin. Do remember to ask for help if you cannot do this by yourself, as there will be some splinters on the back of your arm you may not be able to reach. You can sanitize the tweezers by putting them in boiling water for 10 to 15 minutes. After you have managed to get the largest of the fiberglass out, you should again apply ethyl alcohol on the wounds or pricks left over in order to sanitize them.
If the pieces of fiberglass you have in your arm are too small to use this method, then you should seek medical help at once. It is important that your do this speedily because otherwise, small fragments of any substance can embed themselves in your skin and penetrate deeper to get into your bloodstream as well. After this, there is no telling where all they might travel within your body, and this is an extremely dangerous situation. It is possible that for microscopic pieces, you may have to resort to surgery to remove them.
answered by G M