My one year old has a terrible runny nose so bad yesterday she had a bloody nose. she took zyrtec (cetirizine) at 8:30 this morning can i give her benydryl now?

If not sleepy, yes: Yes even if taken at the same time. Whether it works or not is another question.

You can: but remember that antihistamines dry the nasal tissues and can make them more prone to bleeding. A nasal saline or steroid spray would be a better option.

IMHO, won't help. : There's little evidence that antihistamines do much for viral runny noses, which is a good possibility given your scenario. And particularly for kids under 2, when side effects are more a concern. Bloody nose likely from inflammation; antihist. , steroid sprays may even worsen it. Humidifier in bedroom, gentle nasal saline and time. ENT eval if nosebleeds keep coming back.