Y.M.
I have a lot of experience with the Benedryl because the docs used it all the time on my son when he went through chemo therapy. They gave it to him intrevenously and in the tummy. They used it to help calm him down before giving him a blood transfusion or new meds and they used it in-case of allergic reaction. In children's hospitals it's depensed like candy.
Although I feel guilty with drugging my kid, I have used it to calm him down and break him of some ingrained sleep habits. I only did it when the sleep habit was obviously happening because his body was routinely waking up through the night.
So, if you do decide to use it... you may feel guilty like me. But, I encourage you to only use in the case of a last resort and after you've tried everything.
Tip: She could be waking for legitimate needs like Molars around that age. There's no teething that throws the sleep cycle off day and night like molars. In that case, Tylenol would be the key to some more peaceful sleep. For my baby I had to alternate tylenol and ibuprofen. She had disturbed sleep for over a month but, I could clearly see that her gums were red, puffy, and teeth were putting pressure to come through. In that case, I considered the Benedryl just to have mercy on the poor child and let her get some good sleep. But, I didn't decide to use it, because her waking was normal, natural, and expected due to the situation. So, I just went with the tylenol and ibuprofen.
Maybe, you could try those first. That way you'll know if it is a pain problem. If it is, she'll sleep soundly.
A natural alternative is Tranquil Child drops. Seems to work like a charm without the guilt of drugs that have a noticable impact.
God Bless,
Y.
* The sleep of the saints is sweet. That's a bible promise to count on and pray over this situation... Hope this helps too.