Crack a window open and let some oxygen into the room. Also consider a humidifier. Heaters dry out the moisture in the room which dries up the mucus in your body. That’s what causes the sickness and dry coughing. It’s not as cold where I live as it is in Canada but we haven’t used the heater for more than 30 minutes at a time and we open up the windows daily. No one in my home got sick this year and we have an elderly living with us. 

 Oh and make sure to use filtered water with the humidifier if you choose to get one. You don’t want to inhale all that fluoride and bullshit from your pipes.