Many people assume that all toenails that are discolored, thick, or otherwise abnormal in appearance are infected with toe nail fungus. While in many instances this is true, there are numerous other conditions that can cause discoloration and surface changes to the toenails. These conditions are not treatable by the popular medications used to combat toenail fungus, leading many to believe the medications are not as effective as the research claims against what was assumed to be a fungus infection. This article will cover a few of the most common conditions that can cause toenail changes, so that the difference between fungus and a completely different nail condition can be appreciated.
The most common reason a nail becomes discolored, thickened, oddly shaped, or otherwise abnormal has nothing to do with disease or infection. Most of the time, nail changes are simply due to basic mechanical pressure. The tissue that grows the nail outward (the nail matrix) is quite fragile, and even mild amounts of pressure over time can cause this tissue to grow nail abnormally. This tissue sits over the bone under the base of the nail behind what is commonly called the cuticle. Toes deal with pressure at the top of the toe and at the tip of the toe all day. The pressure can take the form of a single quick event, like a heavy weight dropping on the toe, or gradually, as when someone with a long second toe wears tight fitting shoes frequently. Injuries either directly damage the nail matrix, or cause lifting of the nail from the skin underneath due to pressure from bleeding which in turn harms the nail matrix or the skin under the nail itself. Pressure from shoes due to a poor fit or from toes that are positioned too far upward into the top of the shoe (due to birth position or slowly developing deformities like hammertoes) can lead to thickened, discolored nails. This is due to a build up of the nail itself, or to the hard tissue underneath. This process is irreversible, as the nail matrix is usually permanently damaged, although nail softeners can help dissolve some of the extra keratin (nail and skin material) that builds up in this area. It is also not uncommon for toenails to become more thickened the older we get. This is perhaps due to a combination of all the factors discussed above, or simply due to declining circulation or skin tissue quality in general.
Another common reason nails become discolored or oddly shaped is due to diseases elsewhere in the body. There are numerous conditions that will cause discoloration in the nails. Conditions like heart and kidney disease can cause nails to have red and brown color changes respectively. Liver disease and malnutrition can cause thin white lines to form across the nail from side to side, as can various types of chemical poisoning, such as arsenic and carbon monoxide. Completely white nails can also indicate liver disease, thyroid disease, malnutrition, and diabetes. Blue-grey nails are most often due to simple bleeding under the nail from an injury, but can also indicate silver poisoning. Splinter-like red streaks can be the results of heart infection, cancers elsewhere in the body, pregnancy, as well as various autoimmune-type arthritic and connective tissue diseases like rheumatoid arthritis and lupus. Chemotherapy can also discolor nails in various degrees, and even cause them to become brittle and loose.
Various skin conditions can also change one’s nail appearance. For example, psoriasis can cause pitting of the nail and an oil spot like staining under the nail. Pitting can also be caused by a wide variety of allergic and autoimmune/rheumatological conditions.
The most important nail change that is mistaken for fungus or a bruise appears as a dark streak in the nail. This streak begins at the base of the nail and can run out the end of the nail. Unlike nail bruising, this discoloration is somewhat well contained lengthwise, looking more like a streak and less like a spot. In dark skinned individuals, this is a common finding and usually is benign. In fair skinned individuals, especially those with pigment changes to the skin surrounding the nail streak, this could indicate melanoma. This is a diagnosis that has to be made quickly and accurately, as melanoma can be deadly. Prompt evaluation by a doctor of any new dark streaks in the nail and surrounding skin needs to be made, as assuming it is fungus or a bruise can be a lethal mistake. Symptoms of higher risk factors for melanoma of the nail include a new streak in a light skinned individual, a sudden change (widening, darker etc.) in an existing streak, involvement of only one nail, pigmentation of the skin around the nail, a new streak in an older person (age 60-79), a streak width of more than 3 millimeters, as well as a family history of melanoma.
As one can see, numerous conditions can cause toenail changes. In all fairness, on should not assume every little change to their nail could indicate a significant disease. These types of nail changes are not common, but the underlying point is that not everything is related to fungus when considering the causes of abnormal nails.