Can I take Zyrtec-D while taking Levothyroxine (Synthroid)?

Patient: Hi . I suffer from terrible seasonal allergies. Can I take Zyrtec-d if I also take 88 mcg of synthroid daily?

Symptoms: Sinus headache, dizziness, terrible congestion, sneezing, runny nose, sore itchy throat, itchy watery eyes

Doctor: Yes, it is safe to take an antihistaminic-decongestant preparation like Zyrtec-D while on Levothyroxine (Synthroid). How ever, it is best to take Levothyroxine empty stomach in the morning.