As a first aider we are told not to administer anything nor to take samples from people even if they give consent. This is not only due to legal issues (I kid you not) but also in case the person doesn't do the task correctly (due to panic, etc) i.e. misreads the information on the machine, etc. causing more harm.
Work place first aiders are not trained to do this on the courses they take unless they go beyond the basic training (which few companies will allow). They are expected to know who are diabetics and give sugar water as well as at the first signs to call an ambulance.
There was a case recently where the first aider did administer a persons medication (all correctly and in accordance with the issue of the person at the time) however, the person lied and said they didn't have any medicine prior to the first aiders intervention (all witnessed and documented).
By rights the person should've been up and walking in minutes. Not so. It turned out that the person had self administered minutes before (a double dose in fact) This meant the person had 3 lots of medicine within a few minutes. Obviously the result wasnt good - an ambulance, hosptilisation, etc.
This left the first aider in an extremely bad position as well. They were under a cloud of suspicion until a formal enquiry had finished, they were suspended until the outcome, rumours were rife. The impact on the first aider was terrible - guilt, self doubt, stress, etc.
Even when the person recovered and admitted the extra dosage the first aider never really recovered.
WincyEtNightie - the phrase they use in training is 'no potions, lotions, creams or pills'. I can list a dozen other examples to highlight why but I think you understand some of the potential issues from the above.
It is extremely anoying when people get grumpy at me for not dispensing paracetamol for a headache when I give them an example of why I cant I usually get a smart reply of 'well I wouldn't sue you', etc. However, you might not but your family might or the office might. Not to mention how I'd personally feel knowing I'd hurt a collegue.
Hope that gives an insight.