Pimple on lip or cold sore? How to tell

A spot on or near the lip can be one of several things: an ordinary pimple, a cold sore, a patch of perioral dermatitis, or a mouth ulcer inside the lip. They look alike at first and need different care, and one of them is contagious. This guide explains how to tell them apart and what is safe to do. It is part of Skinli's guide to the types of acne.

Four common causes of a spot on the lip

What it is	How it starts	What it looks like
Pimple	A clogged pore swells	A red bump, sometimes with a white or yellow center of pus
Cold sore	Tingling, itching or burning first	One or more small blisters filled with fluid that burst and crust over
Perioral dermatitis	A rash around the mouth	Many small bumps around the mouth only; the skin may burn or itch
Mouth ulcer	A sore inside the mouth	A blister or sore on the inside of the lip or mouth

The NHS cold sore page gives the cold sore details and a short list of look-alikes: a painful red spot on the face filled with pus is likely a spot or boil, a blister on the inside of the lip or mouth is likely a mouth ulcer, and red sores that become crusty, golden-brown patches may be impetigo, a skin infection. The American Academy of Dermatology (AAD) describes perioral dermatitis.

How to tell a pimple from a cold sore

The biggest clue is how the spot starts. The NHS says a cold sore usually starts with a tingling, itching or burning feeling. Over the next 48 hours, one or more painful blisters appear. The blisters are small and filled with fluid, and later they burst and crust into a scab.

A pimple starts differently. The AAD explains that oil, dead skin cells and bacteria get trapped in a pore, the area swells, and a red bump forms. If it fills with pus, it is called a pustule and often has a white or yellow center. There is no tingling stage and no cluster of clear blisters.

Other clues:

• Where it sits. The AAD says cold sores usually develop on the lip or around the mouth. The NHS adds that the blisters can appear anywhere on the face.
• How often it comes back. The AAD and the NHS say the cold sore virus stays in the body after the sore clears, and sores can come back. Triggers the NHS lists include illness, sunshine and periods.
• How long it lasts. The NHS says cold sores usually clear up on their own within 10 days. The AAD says within two weeks in healthy people.

If you are unsure, a pharmacist or doctor can look. The NHS says to see a GP if a cold sore has not started to heal within 10 days, is large or painful, or if you have a weak immune system.

Why a lip spot should not be popped

The AAD's advice on popping applies to pimples everywhere, and it matters more on the lip. When you squeeze a pimple, you often push pus, dead skin cells and bacteria deeper into the skin. The AAD says that increases swelling and can lead to acne that looks worse, more pain, scars, and infection from the germs on your hands.

If the spot is a cold sore, squeezing spreads the virus. The NHS says not to touch a cold sore, apart from applying antiviral cream, and to wash your hands before and after.

For a painful pimple, the AAD suggests ice, which reduces swelling. A dermatologist can drain or inject a large, painful spot safely.

What causes pimples on and around the lips

Pimples on and around the lips form the same way as any acne. Products that sit on the lips add one more cause. The AAD's makeup page says that if you have tiny breakouts around your lips, your lipstick or lip balm could be the cause. It calls this acne cosmetica, acne caused by products on the skin or hair.

Two facts from the AAD make it hard to spot:

• It can take from a few days to 6 months for the bumps to appear after you start a product.
• It tends to clear once you stop using the product that clogs your pores.

The fix the AAD suggests is to check labels for "oil-free", "non-comedogenic" or "won't clog pores", and to stop products that do not carry one of those terms. It also says not to share makeup, brushes or applicators, since sharing can spread cold sores.

The NHS lists broader causes of acne: hormone changes during puberty, periods, menopause and pregnancy, some medicines, and products that make skin greasy. What causes acne covers those in full.

Perioral dermatitis: many small bumps around the mouth

If the spots are many small bumps in a ring around the mouth, the cause may be perioral dermatitis. The AAD describes it as a breakout that looks like many small pimples but develops only around the mouth. The skin may burn or itch. Sometimes it appears around the eyes or the nose instead.

The AAD says dermatologists recommend treatment, because without it the rash may last for months or years. It is a condition for a dermatologist to diagnose and treat. The forehead and chin acne page covers acne lower on the face.

What is safe to put on a lip spot

Keep acne products off the lips. The adapalene gel label says to avoid contact with the eyes, lips and mouth, and to flush with water if contact happens. Before you put any acne product near your mouth, read its label for a similar warning.

What you can do:

1. Do not touch or squeeze it, as the AAD advises.
2. Use ice for pain, wrapped in a clean cloth.
3. For a pimple on the skin beside the lip, the AAD recommends products with benzoyl peroxide or salicylic acid for red or pus-filled bumps. Keep them off the lip itself, and ask a pharmacist if you are unsure.
4. For a cold sore, the NHS says a pharmacist can recommend antiviral cream, and that it works best when started at the first tingle.
5. Stop any new lip product you started in the months before the bumps appeared.

Habits that lower the chance of lip spots

These steps come from the AAD's pages on makeup, skin care habits and cold sores, and from the NHS cold sore page:

• Keep lip products simple. Choose lip balm and lipstick labeled "oil-free", "non-comedogenic" or "won't clog pores", and keep them to yourself.
• Remove all makeup before bed. The AAD says even non-comedogenic makeup can cause acne if you sleep in it.
• Keep your hands away from your face. The AAD says touching the face during the day can make acne flare.
• Protect your lips from the sun if you get cold sores. The NHS suggests a sunblock lip balm of SPF 15 or above outdoors, since sunshine can set off a cold sore.
• Treat acne on the whole lower face, and keep treatment gels off the lips. The AAD says spreading a thin layer over all the skin that breaks out prevents new spots better than dabbing single ones.

If lip spots appear in the same week every month, along with spots on the chin and jawline, the pattern may be hormonal. Hormonal acne vs regular acne explains that pattern and what doctors offer.

Protecting others

This part only applies to cold sores, and it matters. The NHS says cold sores are contagious from the first tingle until they have completely healed. It warns that kissing a baby while you have a cold sore can lead to neonatal herpes, which is dangerous to newborn babies. The AAD adds: do not share lip balm, towels or razors, and wash your hands after touching the sore.

Acne is not contagious, the AAD says. If you are not sure which one you have, act as if it is a cold sore until a pharmacist or doctor has looked.

When to see a doctor

See a GP, pharmacist or dermatologist if:

• The spot has not started to heal within 10 days, which the NHS gives as the cold sore limit.
• Blisters keep coming back on the lip. A GP can prescribe antiviral tablets, the NHS says.
• The skin around the spot becomes hot, red and swollen, or you feel feverish. The NHS says a boil on the face needs an urgent appointment.
• Your lips swell after using an acne product. The adapalene label lists lip swelling as a sign of an allergic reaction.
• You have many small bumps around the mouth that burn or itch, which may be perioral dermatitis.

For acne across the rest of the face, the complete acne skincare routine gives the daily steps, and Skinli's photo check builds a starting plan from one photo and two questions.