My 17-month-old boy seems to have irritation or small mushrooms at the base of his penis."

It is possible that your 17-month-old son has a fungal infection on his penis. This can often be caused by the area being more moist. Fungal infections typically manifest with redness, itching, and sometimes white discharge. Using an antifungal cream like Canesten (clotrimazole) twice a day for a week can help treat the issue. Keeping the area dry, especially after baths, is important for successful treatment. You should see improvement within a few days, but continue treatment for a full week to prevent a recurrence. If your son has any other symptoms, it would be best to consult a healthcare professional. Fungal infections usually respond well to treatment.