Going sound a strange one.
My son(19) has stomach issue. Not exactly ibs but similar symptoms. So was given Colpermin by GP, Anyway for first 4/5 months they worked great. Then we started to noticed he was getting a lot more side effects. We continued with tablets but have now once he is telling us, when ever he takes one he feels extremely angry. Anyone ever heard of this.The packet and google say nothing about mood swings as a side effect.
Has anyone heard of this?
Can't see how. It's basically peppermint and peanut oil. It does have these too apparently:
White beeswax
Arachis oil
Colloidal Silica
Gelatin, Titanium dioxide
Indigotine (E132)
Eudragit S100
Eudragit L30 D55
Triethyl citrate,
Ammonia solution 10%
Monostearin
Polyethyleneglycol 4000
Talc
Purified Water
Still can't see a reason for anger. It's not a brain or hormonal drug at all.
Could be as simple as just his age,girls etc etc. I have a grandson,who before age 19 was the most sensitive,people pleaser you could wish to meet. By age 20,he began to be the most opinionated,argumentive ,I know it all,lad. So just may have found his feet for a time. He even could be worrying about something,that is personal. They don't tell us everything.😉😉
I am a great supporter of Colpermin and I am not aware of any side effects like you mention. I suppose anything is possible! It is mainly only peppermint oil though. Colpermin is one thing that works for me, never had a problem.
Functional Diarrhoea
Does Colpermin really help? 
Colpermin and Buscopan together?
Son going for a colonoscopy
Colonoscopy not completed because of “unresolved loop” and pain
