Reminder: Just one severe sunburn can double your risk of melanoma, the deadliest form of skin cancer. That lobster red color is bad news no matter what, but when it comes to the short-term consequences, some cases are worse than others. So can sunburn make you sick? Quite possibly, yes.

Usually, soothing aloe gel or a cooling yogurt mask can usually take the “ouch” out. Other times, a little more care is needed—stat. Delving a bit deeper into the science of the sun scorch can help you figure out when you’re facing one of those times.