Okay, I've been in a chemistry lab of some sorts about 6-7 hours of every week for about 2 years now. In this time you won't imagine the amount of things I've spilt on me, and I'm still standing.
But in all seriousness, there is not much of a safety concern about dropping a pill into Marquis reagent as long as you've cleaned it well, but Mandelin reagent is a much higher risk.
Simon's Reagent has these chems which can be dealt with like this:
Sulfuric acid: Let it evapourate in a ventilated area OR wash it with a slightly basic solution (Sodium Bicarbonate would be good)
Formaldehyde: Is quite volatle, dry the pill thoroughly.
The reasoning behind taking a pill that's been dropped in Simon's Reagent and cleaned is the fact that the toxcitiy of the chem you're taking and the binders and contaminants in the pill far outweigh the miniscule amount of formaldehyde and conc. Sulfuric acid.
Also, any reaction between the formaldehyde and the MDXX does not make a toxic compound to my knowledge.
Ammonium Vanadate in Mandelin's reagent is another story. This thing is highly toxic! The LD50 is 58.1mg/kg, so it won't kill you if you eat the pill, cause there's no way you've got the 4 grams needed to kill an average human, but there are very nasty side effects...
But, this is a judgement call on your behalf. If this happened to me, and I dropped it in Simon's reagent. I would take it after a thorough washing. If it was Mandelin's reagent, that is another story.