Don't take any more than 3 or so of these at once. Don't take them too often either.
Pseudoephedrine is a decongestant that works really, really well for some people. It also unfortunately raises blood pressure and can interact negatively with higher doses of DXM (usually 100mg plus)
Acetaminophen is... Tylenol. But too much Tylenol can destroy your liver. Don't take more than 4 grams in a day.
The "active ingredient", what gets you high, is dextromethorphan hydrobromide, or DXM. People get high off of it all the time. At low doses it is like you described, a sort of drunk and almost MDMA-like feeling. At higher doses it can be very mindbending, a lot like being very blackout drunk, or on ketamine.
If you like getting high this way, a few tips:
1. Find a product that *just* contains DXM and nothing else. If you take more than a few pills of most combination cold medicines (like the ones you have, with acetaminophen and pseudo) you can get very very sick and even die. But DXM-only products are relatively safe. They will, in the worst case, just make you sick.
2. Don't abuse DXM. Don't do it every day. Don't even do it every 3-5 days. Keep at least a week between your "trips" or you will find you need more and more to make you feel the same way. And if you do it all the time, every day, it can be a real difficulty getting detoxed.
So just be careful. There's nothing wrong with taking 3 or maybe 4 of your cold pills you have, but don't take any more.
Enjoy your trip by the way.