Vertical nail ridges are most common in older people, as the production of new cells slows down. Our nails grow as living cells group together and multiply beneath the skin, pushing the older cells out into the thing we recognise as our nail. This renewal process reduces as we get older, causing the nails to grow unevenly.
Whilst getting older is a good excuse for most things, it is not the only reason for ridges forming in your nails. This can also be an indication that your body is lacking something important such as iron, protein, calcium, zinc or even vitamin A. Skin conditions such as eczema and psoriasis can also bring about ridges, as can digestive disorders.3
It's worth speaking with a medical professional if you are unsure of the cause of them.
You can also create ridges in your nails through a trauma or injury. This can include hitting the nail, potentially causing a bruise to form underneath the nail, leading to swelling and a change of shape to the nail. This might mean that you also notice brown spots forming, which will gradually heal. If this is the case, you should allow any injuries to heal and see if the ridge grows out. That means it is important to pay attention to those funny little lines.
If you start to notice changes to the colour or texture of your nails as well, including the appearance of dark lines, then it may be a sign of a more serious medical condition, and you should make sure that you speak to a medical professional.3