Can I use Aspirin and other pills

I intend to do The Master Cleanse in a few weeks when I have have the proper time to devote to it. I did a dry run for one day and woke up this morning with a massive headache similar to a hang over. I drink a lot of coffee so I assume this might be cafeine withdrawal.

The question I have: can I use aspirin or Advil on the diet?

thanks for any response
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