If you see this appearing on your lips, it is a sign of ca….

Cold sores—sometimes called fever blisters—are a common skin issue caused by the herpes simplex virus type 1 (HSV-1). Though usually not dangerous, they’re contagious, often painful, and tend to come back once you’ve had them. That’s because the virus stays in your body for life, hiding in nerve cells and reactivating when triggered.

What Brings on Cold Sores?

The main cause is HSV-1, often picked up in childhood through close contact like kissing or sharing items. After the first infection, the virus settles in your body and can remain inactive for long periods.

HSV-1 differs from HSV-2, which is more commonly linked to genital outbreaks—but either virus can affect different areas based on how they’re passed from person to person.

What Can Trigger an Outbreak?

Even if the virus is “sleeping,” certain situations can wake it up and cause a flare-up:

Stress (mental or physical)
Being sick (like catching a cold or having a fever)
Low immunity
Hormonal changes (such as during periods)
Sun exposure (especially on the lips)
Fatigue or lack of sleep
Outbreaks usually appear as sores around the mouth, nose, chin, or cheeks.

Signs to Watch For

Cold sores often give warning signs before showing up:

Tingling, itching, or burning sensations
Redness or swelling near the lips
Then within 24–48 hours:
Blisters appear, often in clusters
They fill with fluid, burst, and form a crust
Healing usually takes 2–4 weeks
Starting treatment early can reduce symptoms and spread.

How to Treat Them

There’s no permanent cure, but treatment can help:

Antiviral medications (like acyclovir or valacyclovir) work best if taken at the first sign
OTC creams with docosanol or lidocaine ease pain and swelling
Pain relievers like ibuprofen or acetaminophen help reduce discomfort