In most cases of ringworm infection, the fungus will glow (fluoresce) if it is exposed to black light. However, this is not necessarily always the case, and other conditions that are similar in appearance to ringworm also fluoresce under black light, including Lyme disease. As such, it is essential to seek medical attention if you think you may have ringworm, even if you have a blacklight at home, as there are other tests that your doctor may run to diagnose ringworm or rule out other more concerning conditions. Our board-certified physicians at Reddy Urgent Care would be happy to take a look at your rash to determine whether or not it is ringworm and what way forward is best for treatment! You can also call us if you have any questions about ringworm, including how we diagnose this condition and what our treatment options are!