Not sure how to title this one! Also, I know that laws/processes may be different as we are in the US vs the UK, but I wasn't sure who else to ask.
A friend of mine has a six year old daughter. She and her DD's father are not together but he has DD every other weekend.
The friend has just found out via his live-in girlfriend that he has been taking steroids for over a year.
Her concerns are A) the illegal nature of it, obviously and B) the effect on his temper/stability. He was jailed years ago for assault on my friend and she really concerned that the steroids will make things worse.
They've had a decent co-parenting relationship in the last few years and I know my friend would like to keep it that way, but her concern for her daughter (and the girlfriend as well) is more important.
Steroids aren't illegal, so far as I know. Often they are prescribed for a range of medical conditions.
They do, I believe, have side effects including increased irritability, but unless there is anything to suggest that his behaviour towards his daughter has changed, I don't think there's anything your friend can do.
In the UK, it's not unusual to have hairshaft testing for drugs, as the residue stays in the hairshaft for much longer than blood or urine. It has, of course, to be ordered by the court and there has to be evidence of illegal drug abuse.