Nails change slowly, so treatment mistakes also take a long time to reveal themselves. Thickening, yellowing and crumbling can be caused by fungal infection, but trauma, psoriasis and other nail disorders can look similar. Treating every abnormal nail as fungus can mean months of unnecessary medication.
One nail or many nails?
A single damaged toenail after repeated shoe trauma tells a different story from several nails gradually thickening with athlete’s foot. Fingernail involvement may have different exposures. Pain, swelling around the nail, pus or a dark changing stripe needs prompt assessment.
Testing can be useful before tablets
When diagnosis is uncertain or prolonged oral antifungal treatment is being considered, microscopy or other testing may help confirm fungal disease. The need depends on the clinical situation.
Nails need patience
Even after the cause is treated, the damaged portion must grow out. Toenails grow especially slowly. This is why photographs taken months apart can be more meaningful than checking day to day.
Related clinic page: General Dermatology