Toenail ridges might appear as a normal part of aging, indicate a serious illness, or serve as a sign of poison ingestion. Ridges also commonly develop after injury to a toenail, which usually becomes discolored. Certain viral and bacterial infections are also linked to toenail ridges, and some medications might produce them.
As part of the diagnostic process, doctors typically look at whether horizontal or vertical toenail ridges appear. Vertical ridges commonly develop gradually as a person ages, extending from the cuticle to the tip of the nail. When toenail ridges suddenly develop without injury, however, they might signal a health condition that needs attention.
Arsenic, chemical poisoning, or plant toxins might lead to fingernail or toenail ridges, which might be accompanied by discoloration. These substances might disrupt cell division, causing nails to stop growing. Nutritional deficiencies, especially with absorption of calcium and lack of iron in the diet, might also show up as nail ridges.
A certain form of toenail ridge, called a Beau’s line, consists of deep grooves across the entire nail surface. These ridges were named after a French doctor who first linked nail ridges to various disorders. Patients with circulatory or thyroid problems might develop nail deformities as symptoms of these disorders. Ridges might also appear in patients with diabetes left uncontrolled by medication or diet.
Some toenail ridges develop from a viral or bacterial infection that has been resolved. This can occur when a high fever affects cells throughout the body. The ridges in the nail indicate when the infection existed, but usually grow out over time.
Doctors typically look for other symptoms when a patient notices ridges on fingernails or toenails, especially when horizontal grooves are present and appear suddenly. Early diagnosis of an underlying condition might prevent serious complications, including vomiting and diarrhea leading to dehydration. If poison is identified as the culprit, treatment should start before organs shut down and the patient lapses into a coma.
When a ridge stems from injury, a patient should watch for infection. Any sign of pus or fluid in the nail bed might require antibiotics. Severe injury to a toenail or fingernail typically causes the nail to darken, and it may fall off. Trauma to a nail also commonly causes pain, which might increase if infection sets in.