1. Petechiae

• Appearance: Tiny, pinpoint red or purple dots that do not blanch (turn white) when pressed.
• Cause: Petechiae occur when small blood vessels (capillaries) break beneath the skin. They can be caused by trauma, straining (like during heavy lifting or vomiting), or certain medical conditions like low platelet count (thrombocytopenia), infections, or blood clotting disorders.
• When to worry: If petechiae appear suddenly and are widespread, or if they’re accompanied by other symptoms like fever, it’s important to seek medical attention immediately.

2. Cherry Angiomas

• Appearance: Small, bright red to dark purple spots, usually round, that may be flat or slightly raised.
• Cause: These are benign growths of blood vessels. Cherry angiomas are common and tend to increase in number as people age.
• When to worry: They are usually harmless, but if a cherry angioma starts to bleed, change in size, shape, or color, or cause discomfort, it’s worth getting checked.

3. Allergic Reaction

• Appearance: Red dots or raised hives, which can vary in size.
• Cause: Allergies to food, medications, or environmental factors (like pollen or insect bites) can cause skin reactions, including red spots.
• When to worry: If the reaction is severe, with symptoms like swelling, difficulty breathing, or dizziness, it could indicate anaphylaxis, which requires immediate medical attention.

4. Heat Rash (Miliaria)

• Appearance: Small red or pink bumps that often appear in areas where sweat is trapped, like under the arms, on the neck, or in skin folds.
• Cause: Heat rash occurs when sweat gets trapped in sweat ducts and causes irritation.
• When to worry: Heat rash is typically harmless but can lead to more serious conditions like a secondary infection if not addressed.

5. Infections (e.g., Viral Exanthems)

• Appearance: Red spots that might spread across the body.
• Cause: Certain viral infections (such as measles, chickenpox, or rubella) can cause red or purple spots as part of a rash.
• When to worry: If the spots are accompanied by a fever, fatigue, or other systemic symptoms, you should see a healthcare provider to rule out a viral or bacterial infection.

6. Dermatologic Conditions

• Psoriasis: Red, scaly patches may appear on the skin, often with silvery scales.
• Eczema: Inflammation that can cause red bumps or patches, often associated with itching.
• When to worry: If the rash persists, spreads, or worsens, you should consult a dermatologist.

7. Insect Bites or Stings

• Appearance: Red, raised bumps, sometimes with a visible puncture mark.
• Cause: Bites from mosquitoes, fleas, bedbugs, or other insects can result in red spots or welts.
• When to worry: If the bites lead to severe swelling, pus, or signs of infection, medical attention may be needed.

8. Rashes from Medications

• Appearance: Red spots or patches may appear after starting a new medication.
• Cause: Some medications can cause allergic reactions or side effects, which can result in a red rash.
• When to worry: If the rash is accompanied by swelling, fever, or difficulty breathing, seek medical help immediately.

9. Bruising

• Appearance: Red, purple, or blue spots that change color as they heal.
• Cause: Bruises can appear from minor trauma or injury, causing blood vessels under the skin to break.
• When to worry: If bruising occurs without any clear cause, or if you experience frequent, unexplained bruises, it might indicate a clotting disorder, and you should seek medical advice.

10. Vasculitis

• Appearance: Red or purple dots (petechiae or purpura) that may form larger patches, typically on the legs.
• Cause: Vasculitis is inflammation of blood vessels, which can cause blood vessels to leak blood into the skin, resulting in red or purple spots.
• When to worry: If you notice these spots and have other symptoms like fever, joint pain, or abdominal pain, it’s important to seek medical attention.

When to See a Doctor:

You should see a healthcare provider if:

• The red dots don’t fade or disappear after a few days.
• The red dots are widespread and seem to be spreading.
• You experience other symptoms like fever, swelling, fatigue, or pain.
• You’ve had recent changes in medications or exposure to allergens.
• You have a history of blood clotting disorders or other serious health conditions.

Always err on the side of caution if you are concerned about new skin changes.