Onychomycosis is a fungal infection of fingernails or toenails. This infection is more common in people with Down syndrome (DS). Toenails are more commonly infected than fingernails.
Why are people with DS more at risk?
Possible reasons people with DS are more at risk for onychomycosis include:
The immune system of many individuals with DS has some impairment that does not allow the body to prevent or destroy the fungus adequately.
Dry skin that cracks can allow infectious agents (such as fungi) to invade the skin and, ultimately, the nails. Dry skin is a common issue for people with DS.
Some individuals with DS are less proficient at self-care. Some people with DS find it challenging to moisturize dry skin appropriately, wash and dry their feet adequately, or change socks when their feet get sweaty.
Other potentially contributing causes that are more common in people with DS include venous insufficiency, obesity, and hallux valgus (bunions).
Occlusive or poor-fitting shoes. Due to the anatomic structure of the feet of many people with DS, finding well-fitting shoes can sometimes be challenging.
Symptoms and physical findings
Onychomycosis often presents with yellow to white discoloration of the nail, initially occurring either at the top or the base of the nail. It can progress to cause thick and brittle nails, splitting of the nails, separation of the nail from the underlying skin, and, infrequently, pain. Often, more than one toenail is infected. Complications include transmission of the fungal infection to other parts of the body or a bacterial skin infection in addition to the fungal infection. However, these complications are quite uncommon in our experience with adolescents and adults with DS.
In addition to the physical exam, diagnostic testing may be recommended. A scraping or clipping may be taken to assess for fungus. The specimen can be examined under a microscope (KOH prep), a fungal culture run in a lab, or additional tests using stains or assessing for fungal DNA. There is some debate as to the necessity to confirm the diagnosis with testing if the physical exam is consistent with onychomycosis.
The first question to answer when considering treatment is how aggressively it needs to be treated. For many, it is primarily a cosmetic issue without pain and with little chance of complications. Based on that, some decide to manage it with conservative measures only while others choose additional treatments. Overall, a toenail fungal infection is mostly harmless and medicated treatments may become cumbersome and cause some side effects. If an individual wishes to forgo any treatment option, at minimum, proper hygiene and trimming of the nails is recommended to keep the area clean and to prevent further infection.
Since onychomycosis is more common in the toenails, we will focus on foot care. The initial step in treating onychomycosis includes proper hygiene of the feet. It is important to wash and dry one’s feet gently but thoroughly at least daily. Keeping the nails trimmed is an important but sometimes difficult part of the management of onychomycosis. Cutting the nails is best done after a shower or bath because the nail is softer and easier to trim. If nail trimming becomes difficult due to the brittleness of the nail, an individual may need to be seen by a podiatrist, a provider specialized in feet and ankle care, to maintain short nail length.
Dietary changes may also benefit in the treatment of onychomycosis. Various diet changes have been recommended including eating probiotic-rich yogurt, a diet rich in essential fatty acids, foods rich in calcium and vitamin D, enough iron to prevent brittle nails, and enough protein to promote nail regrowth.
A variety of topical “home remedies” have been successfully used. These include daily topical treatments with Vicks VapoRub, tea tree oil, vinegar, or others.
Some medicated lotions or creams such as ketoconazole (Nizoral), econazole (Spectazole), and clotrimazole (Lotrimin) can be applied nightly and wrapped with gauze.
Topical prescription medications are also available. An antifungal nail polish called ciclopirox (Penlac) can be applied to the infected nail daily with minimal side effects. The nail polish is removed after a week with alcohol before applying a new coat. This process takes up to a year. Other topical prescriptions include efinaconazole (Jublia) and tavaborole (Kerydin). It is recommended to use these daily for 48 weeks.
Topical treatment takes many months for results to become noticeable, but it can be a good treatment option as many individuals tolerate the topicals with minimal side effects.
Oral medications such as terbinafine (Lamisil) or itraconazole (Sporanox) can be prescribed. One of the possible side effects from these is liver damage, and liver monitoring through blood work may be done. In our experience, liver dysfunction due to these medications is uncommon. These medications are taken for 3 months (for toenails) or shorter courses for fingernails.
Particularly if the nail infection is severe and causes pain for the individual, surgical removal of the toenail can be considered. A new nail will grow in its place, but it may take several months to a year to grow back fully. Sometimes, a combination of ciclopirox (antifungal nail polish) and surgery is needed to help ensure that a healthy nail grows back. Alternatively, as part of the process of removing the nail, the nail bed can be destroyed with medication and the nail won’t grow back. In that situation, the person is left without a protective nail although, in our experience, this is generally tolerated.
Treatment course and effectiveness
Other than surgery, treatments for this infection, as noted above, are recommended for many months. However, due to the slow growth of toenails, it may take even longer for results to be evident. Even after the fungus has been eliminated, it may still take several months for the healthy, non-infected toenail to grow out from the nailbed. A good sign is “proximal clearing” in which the base of the nail, as it becomes visible from under the skin, is normal. As the nail grows, the abnormal parts fall or are clipped off from the distal part of the nail.
In general, oral treatments tend to be more successful than topical treatments. However, all these non-surgical treatments have a significant failure rate. In addition, particularly if the conditions that contributed to the developing the infection are still an issue (see above Why people with DS are more at risk), the recurrence rate can be high with any treatments, including surgery (if the toenail is not permanently removed).