Is this swelling dangerous or can I just let my wisdom tooth grow out?

[halostyx]

My other 3 grew out during the past year, never had swelling.
The first half of this one grew out a while ago, but since yesterday I've had this swelling. Doesn't hurt too much.

 

[Dr M]

This almost looks like a small abscess associated with food impaction or pericoronitis of the unerupted wisdom tooth. I would suggest going to see a dentist, so that an x-ray can be taken in order to evaluate if you have enough space available for the wisdom tooth to erupt. If not, it would be my suggestion to remove that wisdom tooth as well as the opposing one.