What’s this white stuff near the top edges of my niacinamide bottle?
The white stuff forms on the edges when some niacinamide drops there. You probably accidentally dropped some when you were getting the product out.
Niacinamide is a white or off-white crystalline powder. It is usually mixed with liquids in skincare products, so the final product is liquid, but in its natural form, niacinamide is a crystalline powder.
That white stuff on the edges of your bottle is niacinamide in its crystalline form. A small amount of niacinamide must have dropped on the edges, turning into crystal form.
Does this mean your niacinamide product has gone bad?
No, the white stuff on the bottle does not mean the product has gone bad.
But if you find this white stuff on a brand-new bottle, return the product. White stuff at the top of the bottle forms when niacinamide drops, so theoretically, a brand-new bottle should have no white crust. So safer to return the product.
What should I do with this white stuff?
Clean it.
Gently remove it.
But make sure whatever you use to remove it (be it your hands or a tissue) is clean.