Do warm mist humidifiers help with dry skin and allergies?

No: It is my understanding that humidifiers add litle to the humidity of a house (most moisture goes into ceiling and rafters) so these are of little to no benefit for dry skin. What works best is "soaking and trapping". That is soak skin and then trap the moisture within 2 minures with moisturizers. ..And creams are better than lotions and ointments and oils are better than creams..

Humidifiers: Dry sinuses, bloody noses and cracked lips — humidifiers can help soothe these familiar problems caused by dry indoor air. Humidifiers can also help ease symptoms of a cold or another respiratory condition.But be cautious — while humidifiers can be useful, they can actually make you sick if they aren't maintained properly or if humidity levels stay too high.