If you put aspirin pills or vitamin pills in your mouth but spit them out without swallowing, the effect on your body will likely be minimal or negligible. The active ingredients in these pills need to be absorbed into your bloodstream to have an effect, and this primarily occurs when you swallow them.
When you put a pill in your mouth and then spit it out, some small amount of the active ingredients might get absorbed through the oral mucosa, which is the lining of the mouth. However, this absorption is usually limited compared to what happens when the pill is swallowed and goes through the gastrointestinal tract.
It's worth noting that some medications are designed to be taken sublingually, which means placing them under the tongue for absorption through the oral mucosa. However, in those cases, the medications are specially formulated for this purpose, and they are not meant to be swallowed.
If you accidentally put a pill in your mouth and immediately spit it out, it's unlikely to have any significant effect. However, if you are uncertain or concerned about a particular situation, it's always a good idea to consult a healthcare professional for personalized advice. Additionally, be sure to follow the recommended instructions for taking any medications or supplements to ensure their proper and safe use.