We got our first BFP today and I don't know if I can take Allegra??

Hi everyone! We just found out we are pregnant today <a href="https://play.google.com/store/apps/details?id=com.glow.android.nurture">nurture</a> is saying about 4 weeks and 4 days and I didn't know if I can still take my allergy medicine Allegra? I have bad allergies but I don't want to do anything to harm the baby, it's been a long journey to get to a BFP and I'm scared of messing something up and it's now the weekend. Any advice would be great!