Is zithromax safe to use at 6 weeks pregnant?

Pregnancy Category B. Yes it is safe if prescribed by your doctor, Animal reproduction studies have faled to demonstrate a risk to the fetus and there are no adequate and well controlled studies in pregnant women So it is safe.
What did your OB say. It is safe if u need to use it, meds in the 1st trimester should only be used if safe and necessary , any OB ?S should be directed to your ob.