Оніхомікоз (МКХ-10: B35) 🚨

Onychomycosis: Fungal Infection of the Nail Plate

Overview

Onychomycosis is a long-lasting fungal infection affecting the nail unit, which includes the nail plate, nail bed, and sometimes the skin around the nail. It’s caused by dermatophytes, non-dermatophyte moulds, or yeasts (mainly Candida species). This condition is one of the most common nail problems worldwide, making up to half of all nail disorders.

It can affect people of all ages but is more common in adults and older people, especially those with health issues like diabetes, poor circulation, or weakened immune systems. Onychomycosis usually shows up as discoloured, thickened, misshapen, or crumbly nails. It can affect one or several nails, often starting with the toenails and sometimes spreading to the fingernails.

If left untreated, onychomycosis can cause discomfort, lead to secondary bacterial infections, and cause dissatisfaction with the appearance of the nails. It’s also a common way for fungal infections to spread to other parts of the body or to family members.

Types of Onychomycosis

Onychomycosis can appear in different ways depending on how the fungus enters and where it infects the nail:

Distal (Lateral) Subungual Onychomycosis: The most common type. The infection starts under the nail at the hyponychium or side of the nail fold and moves inward along the nail bed. It’s marked by yellow-white discolouration, thickening, debris under the nail, and eventually the nail may lift off (onycholysis);
Proximal Subungual Onychomycosis: Less common. This happens when fungi get into the nail matrix through the skin at the base of the nail. It’s more often seen in people with weakened immune systems. Early signs include discolouration near the lunula (the half-moon at the nail base) and changes to the nail plate close to the cuticle;
White Superficial Onychomycosis: The fungus invades the surface of the nail plate directly, causing white, chalky, or pale yellow spots on the nail’s surface. These spots can join together, making the nail fragile and brittle.

How Onychomycosis Affects the Nail Plate

Depending on how the nail looks and feels, onychomycosis can be divided into:

Normotrophic: The nail keeps its usual thickness and shape but shows patches of discolouration (yellow, white, or brownish) with slight surface changes;
Hypertrophic: The nail becomes thicker, with a build-up of skin under the nail (subungual hyperkeratosis), changes shape, and develops ridges running lengthwise. The nail bed underneath may also thicken and become painful;
Atrophic: The infected nail thins out, becomes fragile, and often partially or completely lifts away from the nail bed (onycholysis).

Diagnosing Onychomycosis

Getting an accurate diagnosis is key before starting antifungal treatment, as other conditions can look similar to fungal nail infections. A clinical check should be backed up by lab tests to identify the exact fungus and rule out other causes like psoriasis, injury, or lichen planus.

Common diagnostic methods include:

Clinical examination: Checking the nail’s colour, texture, thickness, and whether other skin areas (like athlete’s foot) are affected;
Dermatoscopy: Helps spot typical signs such as spikes, lengthwise lines, and debris under the nail;
Wood’s lamp: Can highlight certain fungi that glow under UV light (for example, Microsporum);
Microscopy: Examining nail scrapings with potassium hydroxide (KOH) to look for fungal filaments;
Culture: Growing the fungus in a lab to identify dermatophytes, yeasts, or moulds;
PCR (Polymerase Chain Reaction): A very sensitive and precise test to detect and identify fungal DNA, especially useful in tricky or recurring cases.

Treating Onychomycosis

Treatment usually takes time and often involves a mix of oral and topical antifungal medicines. Success depends on a clear diagnosis, how much of the nail is affected, the type of fungus, and the patient’s overall health.

Oral Antifungal Treatment

Taking antifungal tablets is generally the best approach for moderate to severe infections, especially when:

More than half of the nail plate is affected;
Several nails are infected (especially more than three toenails);
The nail matrix or base is involved;
Topical treatments haven’t worked or aren’t practical;
The patient has a weakened immune system or diabetes;
There’s also athlete’s foot or fungal infection of the hands.

Common oral antifungals include:

Terbinafine: 250 mg daily for 6 weeks (fingernails) up to 12 weeks (toenails);
Itraconazole: 200 mg twice daily for one week each month, repeated for 2–3 months (pulse therapy);
Fluconazole: 150–300 mg once a week for 6–12 months, sometimes used off-label.

Oral treatment requires monitoring liver function, especially for those with existing liver problems, who drink alcohol, or take other liver-affecting medications.

Topical Antifungal Treatment

Topical treatments can work well for mild, surface-level, or limited infections, especially when the nail matrix isn’t involved. They’re also a good option for people who can’t take oral antifungals.

Common topical options include:

Ciclopirox 8% nail lacquer: Applied daily; the nail should be filed once a week;
Efinaconazole 10% solution: Applied once daily for 48 weeks; no need to file the nail;
Tavaborole 5% solution: Applied once daily; approved for distal lateral subungual onychomycosis.

Combining oral and topical treatments is often advised for more widespread infections, aiming for faster clearance and to reduce the chance of relapse.

Preventing Onychomycosis and Relapses

Since fungal spores can linger in the environment, reinfection and relapse are common. Long-term care involves steps to lower the risk of recurrence and limit exposure to triggers.

Foot hygiene: Keep feet clean and dry; change socks daily; rotate shoes to let them air out;
Footwear care: Use antifungal sprays or powders inside shoes; avoid tight or non-breathable footwear;
Public places: Wear sandals in shared showers, pools, gyms, and saunas;
Don’t share nail tools: Use your own clippers and files; make sure pedicure and manicure tools are sterile;
Manage health conditions: Keep diabetes and circulation problems under control to reduce risk;
Regular nail care: Keep nails short and smooth to avoid damage and make it harder for fungus to take hold;
Follow-up after treatment: Repeat tests like cultures or microscopy may be recommended 6–12 months later to confirm the infection is fully cleared.

Summary

Onychomycosis is a common but often overlooked infection of the nails that can cause significant functional, cosmetic, and emotional challenges. Early diagnosis, choosing the right treatment, and sticking to the plan are vital for good results. Combining oral antifungals, topical treatments, and lifestyle changes gives the best chance of long-term success.

Because onychomycosis tends to be chronic and can come back, prevention and patient education are key parts of managing it. Working closely with a dermatologist or podiatrist helps ensure the right diagnosis, safe treatment, and healthy nails over time.