i would call a pharmacy or google it and see what drug interactions stemetil, im allergic to Stemetil
If your doctor or pharmacist told you that you cannot take stemetil when on domperidone, then obviously they know what they are talking about.
You can always speak with the pharmacist who will be able to advise you, if there is not information leaflet enclosed with your medications.
Domperidone is used generally to suppress nausea and vomiting.
Stemetil is used to treat nausea, vomiting and dizziness due to various causes, including migraine (severe headache).
I have learned from the web with regard to the two medicines that you mention and copied and pasted an extrat above, that explains that both Domperidone and Stemetil is used to treat nausea etc. I would conclude that you should not be taking the two medications together, unless this has been instructed by the your doctor who knows your medical history and I presume the medications that you are taking.
If you buy any over the counter meidines, always ask the pharmacist if it is safe to take with any medications that you are already taking.
Best wishes.
your best option to get an accurate answer on this would be to contact your your primary care doctor to check for possible drug interactions. If there is a problem with taking them together, your doctor can immediately take action to adjust your medication(s) as necessary to avoid any adverse reactions. Good luck!