Took one 4 mg dose ant threw up 40 min
Take half dose
Hello and welcome to Ask A Doctor service.
I have reviewed your query and here is may advice.
Kindly let me know which medicine is it and what is the formulation (syrup, capsule etc).
If vomiting happens within 4 hrs, 10 to 30 % medicine can stay in stomach. So half of the dose may be taken, If it can be safely skipped then better to go for next dose at routine time.
Hope this helps. Let me know if I can assist you further.