Is it necessary to use humidifier in the winter?

What are benefits of using a hunidifier ?

Kinda depends I think. We spent the last three months of last year, and the first three of this at sea level, right on the water in WA state. Then moved to 6500 ft in Wyoming. Really dry air there. Within a week I got the nosebleed from hell. We are not talking a drip here, but a flow. Went to the local urgent care, where the dr worked on me for over two hours, and could not get it to stop. So then we drove 75 miles to a hospital, where they had to use cocaine to get it to stop. Thankfully I didn't have to take a drug test the next day. Dr said to put some neosporin type stuff in my nostrils, and get a humidifier. Did both, no more bleeds. We assume that going up in altitude, and to a much dryer air, was the cause, the humidifier was worth the money...

Using a humidifier will also stop the itchy dry winter skin that plagues many people.

OBG: The nose bleeds from Hell were part of the 6 month acclimatization that occurs when most Southerners move up north & into the drier air. I know exactly how you felt!!

A certain amount of humidity makes a living space a lot more comfortable. Too much and you get condensation and mould.

I can tell when it's too dry at my house. I get little splits on the ends of my fingers, and they hurt like the dickens. I also start zapping things after I walk across the carpet -- potentially fatal for my computers.

House humidity comes from many sources -- the shower, cooking, plants, and people. In our house, add a clothesline in the basement and big open kettle on the wood stove.

Our new forced-air natural gas furnace has a humidifier installed. Every year I break down after a while and get the humidifier going on its lowest setting. I suppose this is more energy-efficient as well as being more comfortable, since water vapour holds a lot more heat than air.

Humidifiers help. The issue of mold is particular concern to me so I have to be careful when it comes to using a humidifier. However, I have found that if I drink enough non-caffeinated beverages throughout the day it takes care of the majority of the problem. Cold weather has a sneeky way of sucking the liquid right out of your body. Look at what happens in the fridge it something is not properly sealed. The same thing happens to the body. Having lived in upstate New York, northern Maine, Alaska, Tucson, The Republic of Panama, and Oklahoma (to name a few places) I have found that proper body hydration is the key.

"...I know exactly how you felt!!..."

I felt like I was gonna bleed to death. Scared the crap out of my wife! I could feel the blood coming from waaayyyy up in the sinus cavities, the doctors kept trying to work on the nostril area...

Humidifiers are helpful if you have a forced-air furnace, as forced air systems thoroughly dry the air as they heat.

Radiant heat, from radiators, doesn't dry the air so much, so humidification is not as necessary for these systems.

In other words, it depends on the type of heating system used in the building.

I've found that most do more harm than good. When we ran a humidifier in our bedroom I would have to sleep with a blanket covering my nose as the moisture would gather there and it would get run and get very cold.
The first year we lived in our house we found it had been smoked in because the moisture from the humidifier sitting on the dresser by the wall caused the wall to bleed nasty brown stuff. Its no wonder we were sick so much, we had to buy a sander and sand that stuff out of there then paint everything good.
Now we've learned to only use the cool mist ones because the warm ones just breed nasty crap in them and the heating element rusts out wfter the first use and lets all the rust in the iar too since they are all made so cheaply.