I tried to find this advice in the thread but couldn’t, and I’m surprised since it’s surprisingly common!

Some sweeteners such as aspartame can trigger migraines (also some gut issues) depending on the quantity and person. While most of the people can take them just fine in principle, others suffer migraines a while after taking them. In my case, this was a relative who suffered a lot until finding out by pure chance that certain sweeteners where the reason, but you can find countless cases.