The Causes of Brittle Nails and Slow-Growing Hair

Fact Checked

imacro manicure image by LadyInBlack from

Nails and hair are both made from keratin, and any changes in your body’s keratin production will impact their health. For example, healthy hair and nails should have a certain amount of flexibility. Dehydration or any form of malnutrition can cause your nails and hair to become brittle and easily broken. Their growth rate could also be affected. Causes for brittle nails and slow-growing hair vary; you should consult your doctor to pinpoint the underlying causes and potential treatments.


Brittle nails and slow-growing hair can be an early indicator of more serious medical issues. For example, according to the National Institutes of Health, brittle nails and slow growing hair can be a symptom of hypothyroidism, a condition that affects the thyroid gland and causes it to stop producing the appropriate amount of thyroid hormone. Hypothyroidism is most prevalent among women over the age of 50 and can result in weight gain, fatigue, depression, joint pain and brittle hair and/or nails. In extreme cases, hypothyroidism can lead to a coma. Brittle nails and slow-growing hair can also be a symptom of other medical conditions including liver disease and renal failure.

Nutritional Deficiency

Brittle nails and slow-growing hair can also be an indicator of a nutritional deficiency. The National Institutes of Health report that approximately 20 percent of women have a common form of anemia caused by iron deficiency. One of the symptoms of iron deficiency anemia is brittle nails. Brittle nails, slow-growing hair, and lackluster skin can also be caused by a deficiency in omega-3 fatty acids or a deficiency in one of the B vitamins. The University of Maryland Medical Center reports early studies suggest that supplements of biotin, one of the B vitamins, can improve brittle nails and hair loss.


If you’ve never suffered from brittle nails or slow-growing hair, and have recently started a new medication, you should consult your doctor or pharmacist to determine if this could be a side effect of your medication. Accutane, a medication prescribed to treat severe cystic acne, is just one of the prescription medications which lists brittle nails as a potential side effect for patients.


If your mother, grandmother or other relative showed signs of brittle or thinning hair as they aged, you may find yourself genetically destined to following in their footsteps. Although you may not be able to completely avoid the problem, your doctor may be able to prescribe medication or supplements that can help improve your hair and nail condition.