You can wash your hands but can't wash your phone.
These germs can spread norovirus, salmonella, E. coli, and other diarrheal illnesses. So there's no antiseptic solution to wash it off from phones.
Your friend's phone can be dangerous.
"Studies at University of Arizona showed that 9 out of 10 phones had a potential disease-causing microbe, and 16% tested positive for fecal matter."