Fungal Nail Infections – Onychomycosis
Clinical overview
Fungal nail infection, also known as onychomycosis, may cause the nails to become thickened, brittle, yellow or otherwise discoloured, and occasionally painful. The condition can be challenging to treat. It is caused by microscopic organisms similar to those responsible for athlete’s foot. These organisms grow best in dark, warm, moist environments, including footwear and socks. They develop beneath the nail within the nail bed and feed on keratin, the protein that forms the nail. Infection commonly begins near the nail tip and may produce white or yellow-white areas that appear damaged or non-viable. If the infection extends toward the base of the nail, it may affect the nail root and cause thickened, distorted, or misshapen nail growth. Some patients may notice an unpleasant odour. The infection may also spread to other nails and adjacent skin.
Symptoms and presentation
In the early stages, fungal nail infection may be painless and may cause only minor visible changes compared with a healthy nail. Over time, white or yellowish-tan patches may develop, and the nail may become brittle, split, thicken, or change shape. As distortion progresses, the nail may grow at an abnormal angle and may become ingrown. Pain may occur when a thickened or ingrown nail presses against footwear. This pressure may also contribute to inflammation and, in some cases, secondary bacterial infection. Even in the absence of inflammation, pressure from footwear may make walking, standing, and other daily activities uncomfortable.
Diagnosis
Accurate diagnosis is important because other conditions, including psoriasis, may resemble fungal nail infection. Your podiatrist may be able to diagnose the condition through clinical examination or point of care testing. They may also send a sample to a laboratory to confirm the presence of fungus and identify the type involved.
Causes and risk factors
Many fungi are commonly present in the environment, including dermatophytes—organisms similar to moulds or mildew that do not require sunlight to grow. Warm, moist, dark conditions, such as sweaty shoes and damp socks, promote fungal growth. These fungi feed on keratin, a protein found in skin and nails. Although fungi may be present on the skin surrounding the nails, infection is more likely when the nail or adjacent skin has been damaged, for example by tight footwear, bruising, inflammation from an ingrown nail, or nails that have been cut too short or trimmed incorrectly. Additional risk factors include excessive sweating and athlete’s foot, which is caused by similar fungi. Some individuals are more susceptible to infection, including those with diabetes, poor circulation, or autoimmune conditions. Recurrence may occur even after successful treatment, particularly in susceptible individuals.
Self-care considerations
Topical treatments are often ineffective because the infection develops beneath the nail, where most surface medicines cannot adequately reach. Any improvement visible on the nail surface is therefore often temporary, as infected nail may continue to grow from underneath. Self-treatment generally provides only short-term benefit. A topical antifungal preparation may help reduce the spread of fungus to unaffected nails or nearby skin; however, it is unlikely to resolve an established infection when used alone.
Professional management
Your podiatrist will assess the nail to confirm whether fungal infection is present and to exclude other possible conditions. Once the type of fungus is identified, treatment may include topical solutions, oral medications, or a combination of therapies. Nails may be trimmed and thinned periodically using an electric grinder, and you may be advised to continue specific care measures at home. Surgical or laser treatment may involve removal of part or all of the nail, often combined with medication to reduce the likelihood of recurrence as the new nail grows.
Oral antifungal therapy
Oral antifungal medicines can be highly effective for persistent fungal nail infections. They reach the nail through the bloodstream and help separate infected nail from healthy new nail while eliminating active fungal organisms. Treatment commonly continues for approximately three months. During this period, the medicine accumulates in the growing portion of the nail. After treatment has ceased, it may continue to act within the nail for a further six to nine months, until healthy nail has grown out. Although these medicines may appear costly initially, they may be more economical than prolonged older treatments and may provide a favourable chance of cure. They are generally safe; however, side effects may occur in a small number of patients, and blood tests may be required for monitoring. Your podiatrist will discuss oral therapy and other treatment options with you to determine the most appropriate management plan.
Prevention of recurrence
You may be advised to treat the inside of your footwear, as shoes can become contaminated with fungus. This helps protect healthy new nail from reinfection. To reduce the likelihood of recurrence, keep the feet as dry as possible, and try to increase exposure to UV light (ie direct sunlight). Powder may be used in shoes to absorb perspiration, and synthetic or nylon socks that trap moisture should be avoided. Cotton socks can assist by absorbing moisture and drawing it away from the skin and nails. Keeping feet dry and protecting them from injury are important measures in reducing the risk of fungal infection. Cutting nails too deeply, trimming them incorrectly, or self-treating an ingrown nail may allow fungus to enter beneath the nail. If footwear was contaminated while the infection was present, sanitising it with an antifungal spray may help reduce the risk of fungal nails returning.