How Effectively Does Toothpaste Cure Cold Sore?

Cold sores last for around 7 – 10 days and can be painful. You can try some home remedies to lessen the pain. One such home remedy involves using toothpaste or a combination of toothpaste and salt on the cold sore blister.

Toothpaste on the cold sore could be effective in lessening of pain and healing period. But this home remedy does not heal cold sores overnight.


Cold sores appear on the skin surface around the mouth or on the lips. They resemble fluid-filled blisters, and causative organism usually is the herpes simplex virus.

In this article, we will talk about the effectiveness of toothpaste on a cold sore. Also, we will know how to apply toothpaste and take precautions, if any.

Mechanism of action of toothpaste on a cold sore

The way in which toothpaste works on cold sore is –

Balances the acidic pH

Acidic pH facilitates the survival and replication of Herpes Simplex Virus (HSV). Food that we eat, stress and chemicals in cosmetics can make the pH around our lips acidic. Toothpaste helps to balance this pH and inhibit virus replication.

Dries the blister

Toothpaste on cold sore dries the blister and reduces the time taken by the blister to drain. You shouldn’t burst cold sore blisters, or else there will be scarring.

Prevents the outbreak of cold sores

Toothpaste, when applied before the eruption of a blister, inhibits the growth of the blister and significantly reduces the healing period.

Ingredients in toothpaste

Different ingredients in toothpaste play different roles which help in the healing of the cold sore.

Sodium Lauryl Sulfate (SLS)

SLS is the active ingredient in toothpaste and also in shampoos, soaps, etc. It is responsible for the foaming of toothpaste and also, it has mild antibacterial properties.

SLS causes cold sores when the concentration of this component is more than 5%. In toothpaste, the level of SLS is usually below 2%, and hence instead of worsening of a cold sore, SLS reduces the time the cold sore blister takes to heal. SLS causes desiccation of the blister and also prevents the spread of the virus to other parts of the lip.

Hydrogen peroxide

Hydrogen peroxide is an antioxidant present in some toothpaste. Hydrogen peroxide also has mild antibacterial properties. Hence it can reduce certain structures present in the envelope of the virus and has a positive effect in reducing cold sore.

Some toothpaste also contains triclosan, chlorhexidine which acts against bacteria. Hence they prevent secondary bacterial infection due to a cold sore. Menthol is a constituent in certain toothpaste and serves as an analgesic which reduces the pain.

How to use toothpaste on a cold sore?

The steps about how to apply toothpaste are

  • If you identify the early signs of a cold sore, then buy toothpaste which has the ingredients we discussed above.
  • Wash your hands with soap and water and dry them.
  • Take a small amount of toothpaste on your index finger and apply it on the cold sore or the regions which are paining and you suspect that a cold sore will form.
  • Leave the toothpaste for around 2 hours and wash it off with a damp cloth after 2 hours.
  • Repeat the same procedure three times a day. During the night you can leave the toothpaste on the cold sore overnight and rinse it off in the morning.
  • Apply some petroleum jelly after washing off the toothpaste.
  • Continue doing the same till a scab forms.

This method may or may not be effective for you. If you have a weak immune system, then the cold sore might not heal using this method. Also, if you start applying toothpaste after blister formation, then you will take a longer time to recover.

Precautions to keep in mind while using toothpaste to cure cold sores

  • There are some claims which relate SLS and cancer, but there is not enough evidence to such claims. If you are doubtful about SLS, then you should buy natural toothpaste which doesn’t contain SLS.
  • Some people have irritation while using SLS. You can perform a patch test before applying the toothpaste to the blister. Also, check if you are allergic to any of the other ingredients.
  • Avoid gel type toothpaste. Use the regular toothpaste and not the fancy versions found in stores.
  • Wash your hands and dry them before applying toothpaste on the cold sore. You can use any antibacterial soap to clean your hands.
  • If your cold sore doesn’t heal even after ten days, you should consult a specialist for the cold sore.

Does toothpaste cure cold sores overnight?

No, application of toothpaste does not cure a cold sore overnight. Blisters require around a week to heal. Toothpaste can reduce the pain, gives you some comfort, and maybe reduce the healing period.

Majority toothpaste contains sodium lauryl sulfate (SLS) as the active ingredient. This chemical inhibits the growth of blisters. But if you are allergic to SLS, then it might exacerbate the blister instead of healing.

Usually, there are some early symptoms of a cold sore and they are –

  • Tingling sensation near the lips and mouth.
  • Itching or burning sensation around the lips.
  • Body ache.
  • Pain in the tongue, throat, or mouth.

If you have a history of cold sores, then watch out for the warning signs before cold sore blister formation. So that in the future you can apply toothpaste even before the blister forms and stop the blister in its tracks.

Toothpaste and salt to cure cold sore

Salt has antiseptic properties and also acts as an antimicrobial agent. Toothpaste used in combination with salt is more effective than toothpaste alone.

Salt helps to eliminate the moisture from the blister, reduces swelling and redness. Salt, when applied on an open wound, is painful, but if you follow the steps outlined below, then you will not feel much pain. The steps include

  • Dry the area where the blister is present.
  • Take toothpaste on your finger and sprinkle some salt on it.
  • Apply the mix onto the cold sores and let it stay overnight
  • Wash off the mixture and apply oil or petroleum jelly.

Salt along with toothpaste makes the region non-conducive for virus thus the virus is not able to replicate.

Over to you

Identify the prodromal symptoms of a cold sore. When you experience similar signs, you can start applying toothpaste for faster healing even before the blister forms.


If you frequently get cold sores, then you should visit a doctor and get medical advice. Also, you need to understand that toothpaste will take time to work on the blister and at times may not be effective.

Do not rely solely on toothpaste and get medical advice when the sore doesn’t heal.


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