It does not matter if you're 16 or 70, if you've got to go just go. At worst you should let someone know you're going. We are providing our employers a service by spending literal lives. We are not students or prison inmates and they're not our parents.
I have ibs-d which means I have days where I might need to go all the damn time. Some days I'll spend an hour or more sitting on the toilet while my guts are trying to flush out last week. Thankfully I'm damn decent at my job and my boss understands (I got really lucky boss wise).
Your health is way more important than their profits. Holding it in to often or to long can and will eventually damage you.