Beau's Lines - Symptoms, Causes & Treatment
By ScanSkinAI Editorial Team✓ Reviewed for medical safetyLast updated June 2026
Deep horizontal grooves or ridges that run across the fingernails or toenails. They occur when nail growth is temporarily interrupted by illness, injury, or stress.
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Quick Answer
Beau's lines are deep, horizontal grooves that run across your fingernails or toenails. They happen when nail growth is temporarily paused due to a severe illness, high fever, injury, or significant stress. Because nails grow at a set pace, the position of the line acts like a timeline, showing when the interruption occurred. These lines are not typically dangerous on their own and will gradually grow out as the nail lengthens. However, if they appear on multiple nails without an obvious cause, they may signal an underlying health issue.
Clinical Context
Beau's lines are transverse depressions in the nail plate resulting from temporary cessation of nail matrix activity. The position of the line indicates when the growth interruption occurred (nails grow about 3-4mm per month for fingernails, 1mm per month for toenails). When present on all nails, they indicate a systemic cause. The depth reflects the severity of the insult. First described by French physician Joseph Honoré Simon Beau in 1846.
Symptoms
- Horizontal grooves or depressions across nail plate
- May affect one or multiple nails
- Groove depth varies with severity of insult
- Line moves toward nail tip as nail grows
- May cause nail to break at groove if deep
- No pain or color change
Severity & Progression
Causes & Risk Factors
- Severe illness with high fever
- Chemotherapy or radiation therapy
- Major surgery or trauma
- Severe malnutrition or zinc deficiency
- Peripheral vascular disease (Raynaud's)
- Uncontrolled diabetes
- Local trauma to nail (single nail)
- Severe emotional stress
Treatment & Management
Beau's lines themselves don't require treatment - they're a sign of past nail growth interruption and will grow out over 6-9 months for fingernails or 12-18 months for toenails. Treatment focuses on identifying and addressing any underlying cause if not already known. Protecting nails from trauma, maintaining good nutrition, and managing underlying conditions helps prevent new lines. Deep lines may cause the nail to break at that point; keep nails short if this occurs.
- No specific treatment needed - lines grow out naturally
- Identify and treat underlying cause if unknown
- Time: 6-9 months for fingernails to grow out
- Nutritional support if deficiency suspected
- Gentle nail care to prevent breaking
- Keep nails trimmed if deep grooves
Red Flags & Complications
Seek medical attention if you experience any of the following:
- Nail breakage at deep grooves
- Cosmetic concern
- Rarely, indicates serious underlying condition if unexplained
Self-Care Tips
- Keep nails trimmed to prevent catching or breaking
- Moisturize nails and cuticles
- Protect nails from trauma
- Ensure adequate protein and zinc intake
- Be patient - lines take months to grow out
When to See a Doctor
If lines appear on multiple nails without obvious cause (illness, chemotherapy), if associated with other nail changes, or if you're concerned about an underlying condition
Frequently Asked Questions
What do Beau's lines look like?
Beau's lines appear as deep, horizontal ridges or indentations running from side to side across the nail plate. They do not typically cause pain or changes in nail colour. You might notice them on a single nail if you injured a finger, or across all your nails if the grooves were caused by a widespread illness, severe stress, or medication like chemotherapy.
Why did these horizontal ridges suddenly appear on my nails?
These lines form when a major event temporarily stops your nail cells from growing. Common triggers include high fevers, severe infections, major surgery, intense emotional stress, or treatments like chemotherapy. They can also be caused by uncontrolled diabetes, vascular issues like Raynaud's disease, or a local injury to the nail base. The line simply marks the time your body diverted energy away from growing nails.
How do you get rid of Beau's lines?
There is no specific treatment needed for the lines themselves, as they are essentially a scar of a past event. You just have to wait for them to grow out naturally. While you wait, it helps to keep your nails trimmed and moisturised. If a groove is particularly deep, the nail might be weak and prone to breaking at that spot, so gentle nail care is important.
How long will it take for my nails to look normal again?
It requires patience, as nails grow quite slowly. Fingernails grow about three to four millimetres per month, meaning a line will take roughly six to nine months to completely grow out and disappear. Toenails grow even slower, at about one millimetre per month, so replacing an entire toenail can take anywhere from twelve to eighteen months.
Should I see a doctor about horizontal ridges on my nails?
If you have a single line on one nail from a known injury, you likely do not need medical attention. However, if these horizontal grooves appear across multiple nails and you have not recently had a severe illness, high fever, or chemotherapy, you should consult a doctor. Unexplained Beau's lines can sometimes indicate underlying conditions like vascular disease, diabetes, or severe nutritional deficiencies that need evaluation.
Are horizontal nail ridges the same as vertical ones?
No, they are quite different. Vertical ridges, which run from the cuticle to the tip of the nail, are very common and usually a normal sign of ageing, much like wrinkles on the skin. Horizontal ridges, known as Beau's lines, run side to side and indicate a specific interruption in nail growth caused by an illness, trauma, or systemic health event.
Is there any way to prevent Beau's lines from forming?
Because they are often the result of an unavoidable severe illness, surgery, or chemotherapy, you cannot always prevent them. However, you can reduce your risk by managing chronic conditions like diabetes or Raynaud's disease, maintaining a balanced diet rich in protein and zinc, and protecting your nails from physical trauma. Keeping your overall health stable helps ensure steady, uninterrupted nail growth.
How can ScanSkinAI help with Beau's lines?
ScanSkinAI can analyze photos of your nails to help identify visual features consistent with Beau's lines. However, it is important to remember that our AI is a screening aid and educational tool, not a substitute for professional medical advice. It cannot diagnose underlying health conditions or determine exactly what caused your nail growth to pause. Always see a healthcare provider for an accurate diagnosis and treatment plan.
Medical References
Information on this page is sourced from and verified against reputable medical resources:
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Medical Disclaimer: This information is for educational purposes only and is not intended as medical advice. The content on this page should not be used to diagnose or treat any health problem. Always consult with a qualified healthcare professional for proper medical evaluation, diagnosis, and treatment of your condition.