Those tiny red marks can range from completely harmless to medically urgent, and the difference often lies in their behavior. Cherry angiomas, for example, are common, bright red bumps made of blood vessels that tend to appear with age and usually pose no danger, though they may bleed if scratched. Heat rash and keratosis pilaris also create red bumps that are more annoying than alarming, often improving with cooling the skin, moisturizing, and gentle exfoliation.

More concerning are spots that appear suddenly, don’t fade when pressed, or spread quickly. Petechiae—pinpoint red or purple dots under the skin—can signal infections or blood disorders and should never be ignored, especially if they come with fever, fatigue, or a sore throat. Allergic reactions and medication side effects can also trigger rashes that demand prompt attention. When in doubt, especially with rapid changes, pain, or systemic symptoms, seeking medical advice is the safest choice.