Cold Sores
Cold sores are small clusters of blisters on or around the lip, caused by the herpes simplex virus. The virus stays in the body for life, but episodes get shorter when treatment starts early, and for most people they become less frequent over the years.
Key facts
Cold Sores at a glance.
Typical signs
Tingling followed by clustered blisters
Common locations
Lip border
Expected course
Virus persists; outbreaks can recur
Treatment options
Antivirals started early
What is it?
Top things to know about Cold Sores
- They are caused by herpes simplex. The virus stays latent for life after the first exposure.
- They recur in the same place. Reactivation produces small blisters near the lip border.
- A first infection can differ. It may cause painful mouth and gum inflammation with fever.
- Unusual sores need review. A persistent ulcer should be reassessed, not treated repeatedly.
What it looks like
What Cold Sores looks like
Cold sores are caused by the herpes simplex virus. An outbreak often begins with tingling, itching or burning at the edge of the lip. Within a day or two, a cluster of small fluid-filled blisters appears. The blisters break, ooze and form a yellow crust, and they usually heal within 7 to 10 days without scarring. Outbreaks tend to return in the same spot.
Blister cluster
Small blisters on the lip edge.
Crusting
Yellow crust as it heals.
Near the nose
Can appear around the nostrils.
Where it shows up
Recurrent cold sores commonly occur at the lip border and nearby skin.
Face
Facial locations.
On different skin tones
Cold Sores on different skin tones
Cold sores look similar on all skin tones, as clear blisters followed by yellow crusts. On brown and Black skin, the surrounding skin may look darker or purplish instead of red, and healed spots can leave temporary dark marks.
What happens in Cold Sores?
Herpes simplex virus remains in sensory nerves after the initial infection. Reactivation brings the virus back to nearby skin, where local viral activity can produce grouped blisters.
- Grouped blisters develop: Local viral activity causes a recurring sore.
- Reactivation reaches the skin: The virus travels along a sensory nerve.
- The virus rests in a nerve: Herpes simplex remains after infection.
Causes and triggers
What causes Cold Sores
Causes
Why it happens
Cold sores are caused by the herpes simplex virus. After the first infection, the virus stays in nerves and can reactivate.
Risk factors
Raise the odds
- Past infection
- Weakened immunity
Triggers
Passes it on
- Kissing (Well established)
- Sharing cups, razors and lip balm (Strong link)
When it usually starts
When it usually starts
Cold Sores
The first infection often occurs early in life; recurrent episodes can occur at any age afterward.
Daily care
Daily care for Cold Sores
A lip balm with SPF, used daily
Prevention if your episodes follow sun.
Leave the crust alone
Picking slows healing.
Plain petrolatum ointment over the sore
Keeps the crust from splitting.
Hand washing and not sharing
Worth it around newborns and anyone with eczema.
Cool compresses
Use a cool, damp cloth for temporary comfort; it does not shorten the episode.
Start an agreed cold-sore antiviral plan at the first warning symptoms
Tablets in the warning stage shorten the episode.
Docosanol cream, over the counter
Shortens an episode modestly.
Daily suppressive antiviral treatment
For six or more episodes a year.
Use the agreed early-treatment plan rather than waiting for a full cold-sore blister
An agreed antiviral plan may work best at the warning stage. Later symptoms can still need review and treatment.
Avoid: Strong sun on the lips
The most predictable trigger.
Avoid: Being run down
Fever, flu or a heavy cold keeps the immune system busy.
Avoid: Stress and short sleep
Both make reactivation more likely.
Avoid: Picking the crust
Restarts healing and leaves a longer mark.
Avoid: Touching the sore and then your eye
Herpes simplex in the eye does real damage.
Avoid: Sharing during an episode
Lip balm, drinks, utensils, towels.
Avoid: Kissing while a sore is open
Especially near a newborn or anyone with eczema.
Avoid: Injury to the lip
Dental work, waxing, fillers, laser.
Avoid: Letting the area dry out and crack
A split crust heals slower.
Avoid: Steroid cream on its own
A steroid cream calms the redness and swelling, which looks like improvement, while leaving the virus free to spread further. It also changes the appearance enough to make the sore hard to recognize later. There is a combination cream that pairs a steroid with an antiviral, but a steroid alone on a cold sore is a step backwards.
Treatments
Treatments for Cold Sores
Abreva
The only over-the-counter cream shown to shorten an episode, and only by about half a day. It has to go on at the first tingle and be reapplied five times a day. It is a reasonable thing to keep in a bag, but antiviral tablets started at the same moment do considerably more.
Lip balm with SPF
Strong sun on the lips is one of the most reliable triggers there is, so for anyone whose episodes follow skiing, a beach holiday or long days outdoors, a daily SPF lip balm is genuine prevention rather than lip care. Use it every day rather than only when an episode is due, and keep using it while the mark left behind fades, since sun makes that darker and slower.
Hydrocolloid cold sore patches
A thin gel patch worn over the sore. It keeps the area moist so the crust splits less, it stops fingers reaching the sore, and it contains the fluid that spreads the virus. It does not shorten the episode itself, and it is easier to use once the blisters have opened than at the tingle stage.
Lysine supplements
A popular supplement for preventing episodes, but the studies behind it are small, old and inconsistent. It is not dangerous and some people are convinced by it. It is not a substitute for an antiviral, and it is not something to rely on if your episodes are frequent.
Petrolatum
Plain ointment dabbed over the crust keeps it soft so it does not split each time you talk or eat, which hurts less and leaves less of a mark. Drying the sore out does the opposite of what people expect. Apply it with a clean fingertip or a cotton bud and wash your hands afterwards - it does nothing to the virus itself.
Penciclovir
Penciclovir cream. A prescription antiviral cream applied every two hours while awake for four days. It shortens an episode by around half a day to a day, so a little more than the over-the-counter cream and a lot less than tablets. It is a reasonable option for someone who cannot take the tablets.
Topical Acyclovir
Acyclovir cream. The cream version of the tablet, five times a day for four days. The virus is multiplying deep in the skin cells and traveling in a nerve, so a cream only reaches part of the problem, and the benefit is measured in hours rather than days. If you can take the tablets, take the tablets.
Valacyclovir
The usual first choice, and for a cold sore it is a single day of treatment - two large doses twelve hours apart, started at the first tingle. Taken then, it shortens the episode and can stop a blister forming at all. Started after the blister is out it does much less, which is the whole argument for keeping a course at home.
Famciclovir
An equally effective alternative, taken as a single dose at the first tingle, which suits people who will not manage a second dose later in the day. It is used where valacyclovir does not suit or is not available. It is usually the more expensive of the two.
Acyclovir
The oldest of the antiviral tablets and the cheapest. It works, but it has to be taken five times a day for five days, which is a lot of doses for something that lasts a week anyway. The dose is lowered if your kidneys are not working well.
Daily suppressive treatment
A low dose of the same antiviral taken every day, rather than only during an episode, for people getting roughly six or more a year. It reduces how often they happen substantially and lowers the amount of virus shed in between. The effect stops when the tablets stop, and doctors usually review it after six to twelve months.
Outlook
What to expect with Cold Sores
Most episodes run a week to ten days. People settle into a rhythm - one or two a year, or several, and some have one episode and never another. Frequency drops with age.
- 1
Warning · Hours 6 to 24
Tingling, itching, burning or tightness in one small spot on the lip. Nothing visible yet.
- 2
Blistering · Days 1 to 2
A cluster of small, tense blisters on a red or swollen base.
- 3
Open · Days 2 to 4
The blisters break, leaving a shallow, weeping raw patch.
- 4
Crusting · Days 4 to 8
It cracks when the lip moves, which is why it bleeds a little.
- 5
Healing · Days 8 to 10
The crust comes away, leaving skin that is pink, or brown to gray on deeper skin tones. They heal without scarring unless picked repeatedly or infected with bacteria.
Complications
Complications
- Associated concerns
Herpes can occasionally spread to the eye or extensively through eczema-affected skin. Eye pain, widespread painful blisters, or exposure of a newborn requires prompt medical advice.
When to get help
When to get help
When to seek care
Seek care for severe, frequent or persistent episodes. Eye pain or redness, widespread blisters with eczema, or illness in a newborn needs urgent assessment.
Questions
Questions you might be asking.
How did I get this?
Almost certainly in childhood, from ordinary contact with someone who carried the virus - a kiss, a shared cup or spoon. Most people have no memory of it, because the first infection often causes nothing. It is not about hygiene or anything you did.
How long am I contagious?
Most easily passed on from when blisters appear until the sore has fully crusted - roughly the first four to five days. Small amounts are shed when nothing is visible. Precautions matter most around newborns, eczema and anyone immune-suppressed.
Why do I always get it in exactly the same place?
Because the virus lives in one nerve, which supplies one small patch of skin. When it reactivates it travels down to that patch. Some people have two or three usual spots.
Will it ever go away for good?
The virus stays in the body permanently, so there is no cure. But episodes usually become less frequent over the years, and daily suppressive treatment can reduce them a great deal. Plenty of people effectively stop having them.
Is it safe to kiss my baby?
Not while you have an active sore. Herpes simplex is dangerous in newborns in a way it is not in older children or adults. Do not kiss the baby, wash your hands before handling them, and cover the sore. If a newborn develops blisters or a fever, or becomes unusually sleepy or floppy, that is an emergency.
Does the treatment work if I start it late?
Less well. Antiviral tablets stop the virus multiplying, and by the time blisters are out most of that has happened. Still worth taking for a severe episode, but the benefit is in the first 24 hours.
Sources
Sources and further reading
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Cold Sores vs Pimple on the Lip
Fordyce Spots vs Cold Sores
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