Brief Answer:
These will have combined sedative effect

Detailed Answer:
Hello and welcome to Ask A Doctor service.

I have reviewed your query and here is my advice.

These three medicines - melatonin, meclizine and fexofenadine, will have a combined sedative effect and there maybe impaired judgement and sleepiness as a result.

Hope this helps. Let me know if I can assist you further.
Dr Vaishalee

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Brief Answer:
Melatonin is a sleep medicine

Detailed Answer:
Hi again

Thanks for reverting back.

Melatonin is a sleep inducer and will have no effect on allergies.
Meclizine is an anti-histamine but has major effect on vomiting. Only slight effect on allergic symptoms.

Among the three, only fexofenadine will have a modest effect on allergies. If ineffective alone, it can be combined with half dose of any other anti-allergic.
It may also be taken in combination of montelukast or a bronchodlator like acebrophylline/salbutamol (if shortness of breath is present).

Basically avoiding the allergen is mainstay of management. Drinking cleaner water from RO system may also help avoid some water based allergens. Polluted air is to be avoided.

Hope this helps. Let me know if I can assist you further.
Dr Vaishalee

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