Can someone explain why antihistamines and cough suppressants don't mix with MAOIs

Antihistaminics do not mix with MAOIs because:
Antihistmainics have anticholinergic activity by this way increase the response of sympathetic nerve and make suppresion of parasympathetic nerve by this way Antihistaminics+MAOIs->causes high response of sympathetic nerve and may cause heart problem and other problems

the anti-histamines r not a problem- it is fine to use them in conjunction with MAOIs. however, decongestants with pseudoephedrine cannot be used with MAOIs because of hypertensive crisis. some cough suppressants also have pseudoephedrine in them. also, dextromethorphan is a narcotic sometimes used in cough suppressants- it should also be avoided for the same reason.

you need to read the label of ur cough medicine carefully- as long as those 2 things r not in the ingredients, it should be fine to use.

MAOIs can cause severe side effects such as sudden high blood pressure. They also interact with central nervous system (CNS) depressants, such as antihistamines or cough suppressants, increasing the CNS depression caused by these drugs. When combined with dextromethorphan, a common OTC cough suppressant, the MAOI can cause a lethal reaction. Any drug that acts on epinephrine, norepinephrine, or dopamine must be eliminated or reduced greatly in patients receiving MAOI therapy.