Nail Health · 7 min read

Horizontal Ridges in Nails: What They Mean and When to Worry

Most nail ridges are harmless. But there is one kind worth paying closer attention to: ridges that run across the nail, from one side to the other. Unlike the common vertical lines that come with age, deep horizontal ridges can sometimes be your body's way of telling you something happened. Here is how to tell the difference, what horizontal ridges usually mean, and when it is worth a conversation with your doctor.

Horizontal vs. vertical: why the direction matters

This is the most important thing to understand, so let's make it simple:

• Vertical ridges run from the cuticle to the tip (up and down). These are extremely common after 40 and are almost always a normal, harmless part of aging.
• Horizontal ridges run side to side, across the nail. These are less common and can point to something worth checking — an illness, stress on the body, a nutritional gap, or an injury to the nail.

So if the grooves on your nails go up and down, you can relax. If they go across, it is worth reading on.

What deep horizontal ridges can mean

Deep horizontal lines across the nail are sometimes called Beau's lines. They form when nail growth is briefly interrupted at the base. Common reasons include:

• A period of illness, high fever, or infection in the previous months.
• Significant physical or emotional stress on the body.
• A nutritional deficiency, such as low zinc, iron, or protein.
• An injury to the nail or aggressive manicures.
• Certain medications or medical conditions.

Because nails grow slowly, a horizontal ridge is often a record of something that happened weeks or even months ago — which is why it can appear seemingly out of nowhere.

What you can do to support healthy new growth

You cannot "erase" a horizontal ridge — it has to grow out, which takes a few months. What you can do is support strong, healthy new nail growth and keep the nail protected while the ridge grows past the tip.

1. Keep nails hydrated and protected

Dry nails are more fragile and more prone to further damage. A nightly cuticle oil keeps the nail flexible and conditioned as it grows out.

2. Support your nails from the inside

Since horizontal ridges can be linked to nutrition, make sure you are eating enough protein and getting key nutrients. A biotin supplement may also help support healthier nail growth over a few months. Check with your doctor first, especially if the ridges came with other symptoms.

3. Be gentle — do not file ridges away

It is tempting to buff a horizontal ridge flat, but sanding it down thins the nail and makes it weaker right where it is already fragile. Instead, keep nails short and smooth with a gentle glass file, and let the ridge grow out on its own.

The bottom line

Vertical ridges are a normal part of getting older. Horizontal ridges are worth a second look — they are often a harmless record of a past illness or stress, but when they appear across several nails, they are worth mentioning to your doctor. In the meantime, keep your nails hydrated, well-nourished, and gently cared for, and healthy new nail will grow in to replace them.