Is it safe to take 1 tablet of 10mg phenergan (promethazine) per day for pupps at 37 weeks of gestation?

Yes. This skin condition, peculiar to pregnancy, will get better when you deliver. It may take a few days to weeks to subside. It is not dangerous and only needs treatment to help with the itching. Antihistamines, such as phenergan, (promethazine) Hydroxyzine and Diphenhydramine can be used safely to cut down on the itching.