Read the package contraindications and if it says don't take if you have thyroid disease than don't take it! Before I knew this I would take these things and become hyper agitated and insomniac. Even heart palpatations. I don't take anything anymore. I get those shots for allergies and now I am fine...no more hayfever.
I was recently informed the best way to take additinal meds with your thyroid medication is take you Rx thyroid meds at least 2 to 4 hours apart from another. Same with supplements. Any thyroid meds absorbsbetter in an empty stomach Take it when you are empty with a large glass of water. Then later 2-4 hours eat and take your other medication
I always take allergy meds. Usually prescription strength and have never heard of not being able to take them while hypo. When I was hyper I couldn't take anything with an added decongestant b/c of bp, but that's the only restriction I know of.