Beau’s Lines on Nails: Causes, Meaning, and Timeline

Last reviewed: 2026-08-09

Quick answer

Beau’s lines are horizontal dents or grooves that run across the nail, and they appear when something interrupts nail growth for a while. The usual causes are a significant illness with high fever, a major stress event, an injury to the nail, or certain medications such as chemotherapy. They are not dangerous themselves: the nail resumes growing and the line grows out over months, but new or repeating lines are worth mentioning to a doctor.

On this page

• What Beau’s lines look like
• Common causes
• Reading the timeline
• Is it serious?
• What your body might be telling you
• What you can do
• FAQ

What it looks like

Beau’s lines are grooves or dents that run side to side across the nail, like a trench cut into the surface. They can appear on one nail or several at once. When several nails show a line at the same distance from the cuticle, it usually means one event paused growth across the body at the same time.

A deeper or longer pause makes a deeper line. A very severe pause can make the nail stop growing almost entirely and shed, which doctors call onychomadesis. Multiple evenly spaced lines can appear when the cause happened in cycles, such as repeated chemotherapy treatments.

Common causes

Most common

• A significant illness, especially one with a high fever, such as a severe flu, pneumonia, measles, or COVID-19.
• Major physical stress or trauma, including surgery or a serious injury.
• Injury directly to the nail or fingertip, like slamming a finger in a door.
• Chemotherapy and some other medications that pause nail growth.

Less common

• Severe emotional stress or a major life event that affects the body.
• Metabolic or circulatory conditions that reduce nail growth.
• Prolonged use of certain nail treatments, such as long-term acrylic or gel nails with damage.

Rare or pattern-specific

• Conditions that cause repeated growth pauses, which show up as several evenly spaced lines.
• Serious systemic illness where nail changes are one of several signs.

Reading the timeline

This is the most useful part of understanding Beau’s lines: nails grow at a fairly steady rate, so the position of the line tells you roughly when the pause happened.

• Fingernails grow about 3 mm per month on average, and a full fingernail renews in about 6 months.
• A line close to the cuticle is recent, within the last few weeks.
• A line in the middle of the nail points back about 2 to 3 months.
• A line near the tip is older, and it will grow out completely within months.

Toenails grow more slowly, so the same math stretches out: a Beau’s line on a toenail takes longer to grow out.

Is it serious?

Usually benign. One shallow line that followed a known illness, fever, or stressful event, with normal growth resuming after. It will grow out on its own.

Worth a mention at a checkup. A deep groove, lines on several nails you cannot connect to any illness or stress, or a line that seems to be moving very slowly.

See a doctor if:

• You have Beau’s lines but no memory of an illness, fever, injury, or medication that could explain them.
• Lines keep appearing, which can point to a repeating cause that needs investigation.
• The nail is shedding or lifting significantly (onychomadesis).
• Nail changes come with other symptoms like fatigue, weight change, or skin changes.
• You are in cancer treatment and notice nail changes, which are common and worth discussing with your care team.

What your body might be telling you

Straight answer: Beau’s lines are a record of events, not a nutrient message. (Lengthwise ridges are a different pattern, usually aging-related, covered in vertical ridges on nails.) They mark a moment when the body paused nail production, and the pause is almost always illness, stress, treatment, or injury.

• No vitamin deficiency causes Beau’s lines, and no supplement erases one. The line is history, not a deficiency.
• Nutrient shortfalls affect nail growth slowly and evenly, not as a sudden single dent. A one-time horizontal groove is a different story from chronic ridging or brittleness.
• The honest interpretation: if you can connect the line to a rough patch of illness or stress a few months back, that is the explanation, and the nail will grow it out. If you cannot, that is when a doctor’s look is worthwhile.

What you can do

• Connect the dots. Think back over the last few months: any high fever, hospital stay, surgery, major stress, or new medication around the time the line would have formed?
• Take a photo and mark the date. Watching the line move toward the tip over the following months confirms healthy growth resumed.
• Protect the nail while the groove is present, since dents can snag and split. Keep nails trimmed and moisturized.
• Do not try to buff the line away aggressively. It is a surface record of growth, and thinning the nail to remove it does more harm than good.
• Eat normally and keep general health habits steady, not because it erases the line, but because steady health supports steady nail growth going forward.
• Mention repeating or unexplained lines to a doctor rather than dismissing them.

FAQ

What causes Beau’s lines on nails? Anything that interrupts nail growth for a while: a significant illness with high fever, major stress, surgery, injury to the nail, or medications like chemotherapy. The line marks when the pause happened.

Are Beau’s lines a sign of a vitamin deficiency? No. Beau’s lines come from a growth pause, typically illness, stress, or treatment. They are not a deficiency sign, and supplements do not remove them.

How long do Beau’s lines take to go away? As long as the nail takes to grow out, about 6 months for fingernails and longer for toenails. The line moves toward the tip as new nail grows in behind it.

Can I tell when the illness happened from the line? Roughly, yes. Fingernails grow about 3 mm a month, so a line near the cuticle is recent and a line mid-nail points back about 2 to 3 months. That is why several nails often show the line at the same spot: one event paused them together.

When should I worry about Beau’s lines? When they appear with no explainable illness or stress, when they keep repeating, or when the nail is shedding or lifting. Those situations deserve a medical look.

Explore more: this guide is part of the complete library, what your nails say about your health.

Sources

• Cleveland Clinic: Beau’s Lines, What It Looks Like, Causes and Treatment. https://my.clevelandclinic.org/health/symptoms/22906-beaus-lines
• Verywell Health: What Causes Beau’s Lines and How Do You Get Rid of Them? https://www.verywellhealth.com/beaus-lines-7108246
• DermNet NZ: Drug-induced nail disease (Beau lines and onychomadesis). https://dermnetnz.org/topics/drug-induced-nail-disease
• Mayo Clinic Proceedings: Multiple Beau Lines and Onychomadesis. https://www.mayoclinicproceedings.org/article/S0025-6196(23)00288-4/fulltext

Disclaimer

This article is for information only and is not medical advice. Always consult a qualified healthcare provider about your health.

Reviewed by the VI Editorial Team. Last reviewed: August 9, 2026