If they start to get over two inches you start to run into all kinds of foot problems ranging from hammer toes to nerve damage, and even problems in the leg.
So wear them in moderation. Many of us wear skinny jeans but don't get them too tight.
You can start to see stomach-related problems such as bloating, indigestion, or heart burn. As well as nerve-related problems from nerves getting getting pinched and irritated, which would cause burning, numbness, some sensitivity changes in the thigh.
And what about what you wear under those jeans. If it's a thong, you are probably okay, that is if you don't find them uncomfortable. What your underwear is made of is probably more important than the cut.
More delicate materials like silk or breathable cotton that doesn't trap in humidity.
Dangly earrings are popular but if they are too heavy they can elongate the hole in your ear. And if they get snagged on something you can tear your earlobe. Wearing earrings that contain nickel give some people a rash.
As with many fashion items, don't wear them for an extended period of time, and just be smart. Looking good without damaging your health is what it's all about.