How To Stop A Cold Sore From Forming

What is a cold sore

A cold sore is a collection of small blisters or bumps on and around the mouth area. They are caused by the herpes simplex virus and are highly contagious, spread through physical touch or sharing items that have come into contact with the affected area. They usually clear up without medication, but there are certain products you can use to help them clear up quicker.

Ways to stop a cold sore from forming

Cold sores usually heal without the need for treatment in around 7-10 days.1 People with a weak immune system may experience recurrent cold sores.2 

There are some methods that can help to prevent a cold sore from forming. If you can feel a tingling or burning sensation before any visible signs of a cold sore, this is the best time to start using antiviral medication and taking preventative measures.

It can also be useful to identify what triggers your cold sores. For many people, specific foods and drinks, such as citrus fruits, can trigger a cold sore.3 For other people, sunlight, stress, or menstruation can cause cold sores to develop more often.

Symptoms, causes, and treatment

Symptoms of cold sores

Symptoms of a cold sore may include:

  • A tingling or burning sensation of the affected area, even before there is any visible cold sore
  • Solid lumps or fluid-filled sores under the lip or skin that is sensitive or painful to the touch
  • A blister, or several small blisters or bumps on or around the mouth

After the initial development of small, sore bumps around the mouth, they may begin to ooze, and after 24-48 hours the cold sores will scab and blister.1 The cold sore itself usually fully heals within 7-10 days, but this may be longer if you have a weaker immune system or another illness at the same time.

Some people can confuse their cold sore symptoms with canker sores. A canker sore is different from a cold sore in that they usually form on the inside of the mouth rather than the outside and have a less crusty or blistered appearance. They are round, white spots with raised edges, and are not contagious.6 If you are unsure as to whether you have a cold sore or a canker sore, refrain from kissing, participating in oral sex, or sharing crockery and speak to a pharmacist or doctor. 

If you have a cold sore, please take extra precautions around people with a weak immune system, babies, and pregnant women.1

Causes of cold sores

A cold sore is caused by the herpes simplex virus which can be passed on by kissing and sharing crockery. Once the virus is inside your body, you cannot be cured of it. It periodically causes cold sores, and it is believed that the frequency is affected by your immune system and stress levels.

Some of the triggers for cold sores that cause more frequent outbreaks include:1,2

  • Hormonal changes, such as during menstruation
  • Excessive stress or a traumatic event
  • An illness that changes or weakens your immune system, such as a cold or the flu
  • A fever or a high temperature
  • Having an infection such as a respiratory tract infection
  • Exposure to the sun

Ways to stop cold sores from forming

It can be difficult to know when you are getting a cold sore. To stop a cold sore from forming, there are preventative measures you can try. 

Avoid touching the area

As cold sores are easy to spread, if you touch your cold sore you must wash your hands immediately to prevent the cold sore from spreading to other parts of your body. This includes your face and genitals.1

Know your cold sore triggers

For many people that have the herpes virus, it can be certain foods and drinks that trigger a cold sore or cause them to develop more frequently. Acidic foods and spicy foods are common cold sore triggers.3

The herpes virus requires an amino acid found in foods called arginine to replicate within your body. It may be useful to eat fewer foods that contain arginine, as this is the main energy source the herpes virus uses to grow. Instead, eating plenty of lysine may help to prevent cold sores as it blocks arginine, causing the virus to stop replicating. Foods that are high in lysine include meat, fish, and eggs.3

Know when to start using medication

Some people report that they feel a tingling or soreness in the area where a cold sore is forming around one day before the cold sore begins to develop.1,2 This is the best time to begin applying antiviral creams or cold sore patches to prevent your cold sore from forming. 


For some people, stress causes cold sores to develop more frequently. Trying to manage your stress levels may help you prevent the formation of cold sores. Some ways to help manage your stress include:5

  • Take care of your body. Engage in physical activity, meditation, yoga, or deep breathing exercises 
  • Ensure you get plenty of sleep
  • Talk to others. Share your worries and stresses with friends and family
  • Take time for yourself. Unwind, do a hobby, and take a break from social media

Exposure to the sun may also cause cold sores to develop more often. To avoid this, take precautions to avoid excessive sun exposure and wear SPF. You can also buy SPF lip products.2

Treatment for cold sores

A cold sore will usually fully heal on its own within 7-10 days.1 However, to help treat your cold sore, you can purchase antiviral medications in the form of antiviral creams, applied every 3-4 hours. Cold sore patches are also available. When placed on the affected area, they can help with wound healing.

These treatments can also be used if you believe you are beginning to develop a cold sore. In severe cases of recurrent and troublesome cold sores, you may be prescribed antiviral tablets. These help to suppress the herpes virus.1


How common are cold sores?

Cold sores are very common. In fact, 67% of people under the age of 50 are infected with herpes simplex virus 1 which causes cold sores. That means over 3.7 billion people have the virus.4

Who is mostly affected by cold sores?

Cold sores tend to affect everyone who has been exposed to the herpes simplex virus equally. However, those who have a weaker immune system may have recurrent cold sores. This means they develop cold sores more regularly and they may last longer than usual.2 

When should I see my doctor about my cold sores?

If you repeatedly suffer from frequent outbreaks or recurrent cold sores, it may be advisable to talk to a healthcare professional. Speaking with a pharmacist first is best, and they can advise specific antiviral medications or a doctor's appointment if necessary.1,2


Cold sores are mouth sores or blisters caused by the herpes simplex virus. They are highly contagious and can be very painful and uncomfortable. Cold sores usually clear up on their own in 7-10 days, but healing time depends on your immune system. To prevent cold sores from forming as often, avoid foods that trigger your cold sore and use antiviral treatments. 

It is also important to avoid spreading the cold sore to other areas of your body and other people, especially those that have a weak immune system. To treat a cold sore, you can apply antiviral creams or cold sore patches that help the wound heal quicker.


  1. NHS Inform. Cold sore [Internet]; 2023. Available from: [Accessed 30/1/23]
  1. NHS. Cold sores [Internet]; 2020. Available from: [Accessed 30/1/23]
  1. Victoria Dental Centre. Foods to Avoid during a Cold Sore Break [Internet]; undated. Available from:,reducing%20salt%20and%20spice%20consumption. [Accessed 29/01/23]
  1. World Health Organisation. Globally, an estimated two thirds of the population under 50 are infected with herpex simplex virus type 1 [Internet]; 2015. Available from: [Accessed 29/01/23]
  1. Centres for Disease Control and Prevention. Coping with Stress [Internet]; 2021. Available from: [Accessed 29/01/23]
  1. National Library of Medicine. Canker sores (mouth ulcers): Overview. InformedHealth.Org [Internet]; 2019. Available from: [Accessed 31/01/23]
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

Get our health newsletter

Get daily health and wellness advice from our medical team.
Your privacy is important to us. Any information you provide to this website may be placed by us on our servers. If you do not agree do not provide the information.

Laura Preece

BSc Pharmaceutical Sciences and MRes Pharmacy and Pharmaceutical Sciences
I am a researcher and medical writer with a passion for pharmaceutics, disease and biological sciences. I am currently researching cellular and molecular biology, investigating the use of vitamin C as an adjunctive therapy for diabetes mellitus.

Leave a Reply

Your email address will not be published. Required fields are marked * presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
Klarity / Managed Self Ltd
Alum House
5 Alum Chine Road
Westbourne Bournemouth BH4 8DT
VAT Number: 362 5758 74
Company Number: 10696687

Phone Number:

 +44 20 3239 9818