Yes, hot compresses during Bell’s palsy can help to alleviate the damaging factor if the facial palsy was caused by swelling. The idea behind hot compress is that we do everything we can to improve the blood and lymph circulation in the area in order to reduce as much as possible the swelling and compression of the facial nerve.
Hot compresses can help during the acute stage of Bell’s palsy
In 99% of the cases, the damage to the facial nerve during facial palsy happens in the pyramid of a temporal bone. There is a narrow channel that is quite long, up to 33mm long, and it has an “S” shape. In that channel, the facial nerve is very vulnerable. So if there is any inflammation, any disruption in blood supply or any other external factor that affects that area, the facial nerve can sustain an injury. Most of the time it happens due to compression.

Do not apply the compress to the face.
We apply the heat to the damaged area, just behind the ear. We do not apply the heat to the face, because that is not where the damage to the nerve happens. During Bell’s palsy, your facial muscles are not affected. Only your facial nerve is damaged. The facial muscles stop functioning because, due to the damage to the nerve in the pyramid of the temporal bone, the signals cannot pass further and do not reach them.
That is why a hot compress can be good. The sooner we reduce the swelling, the smaller is the compression and the lower is the probability of severe damage to the nerve. Of course, use the hot compresses with moderation. Do not overuse them. Make sure you feel comfortable with it, and it is not burning your skin. Also, applying gentle massage to the area and to the face can further help to improve blood and lymphatic circulation.
Avoid cold compresses
For the same reasons, we should avoid cold compresses. The application of cold will have the opposite effect of warmth. It will constrict the blood vessels and can make the swelling worse, as the build-up of liquids (lymph, blood) will have a more difficult time trying to move away from the site of damage.