Also called: Fever blister · Oral herpes
Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.
About Cold Sores
Cold sores are caused by a contagious virus called herpes simplex virus (HSV). There are two types of HSV. Type 1 usually causes oral herpes, or cold sores. Type 1 herpes virus infects more than half of the U.S. population by the time they reach their 20s. Type 2 usually affects the genital area.
Some people have no symptoms from the infection. But others develop painful and unsightly cold sores. Cold sores usually occur outside the mouth, on or around the lips. When they are inside the mouth, they are usually on the gums or the roof of the mouth. They are not the same as canker sores, which are not contagious.
There is no cure for cold sores. They normally go away on their own in a few weeks. Antiviral medicines can help them heal faster. They can also help to prevent cold sores in people who often get them. Other medicines can help with the pain and discomfort of the sores. These include ointments that numb the blisters, soften the crusts of the sores, or dry them out. Protecting your lips from the sun with sunblock lip balm can also help.
It sits within Infections and Mouth and Teeth.
When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.
Research on Cold Sores
58 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.
What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.
Research currently under way
- Viral Infections in Healthy and Immunocompromised HostsNational Institute of Allergy and Infectious Diseases (NIAID)
Research already completed
- Efficacy and Safety of Acyclovir-penciclovir Cream Versus an Abreva in the Suppression of Herpes Simplex Virus EruptionsUniversity of Utah
- EDTA Eye Drops Compared to Abreva for Herpes Simplex Virus EruptionsUniversity of Utah
- A Study to Compare Sitavig (Acyclovir) Buccal Tablet With a Placebo in the Treatment of Herpes Labialis in Participants Whose Immune System Works NormallyBayer
- Post-marketing Study for the Evaluation of Profilm Cold Soresi+Med S.Coop.
- Implementation of a Minor Ailment Service in Community Pharmacy PracticeUniversidad de Granada
- Treatment of Herpes Labialis by Photodynamic TherapyUniversity of Nove de Julho
Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.
Where to read more
Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.
Start Here
- Cold SoreMayo Foundation for Medical Education and Research
- Fever Blisters and Canker SoresNational Institute of Dental and Craniofacial Research
Related Issues
- Can You Get Genital Herpes from a Cold Sore?Nemours Foundation
Clinical Trials
- ClinicalTrials.gov: Herpes LabialisNational Institutes of Health
Medical subject headings
Clinicians and researchers index this subject under Herpes Labialis. These are the terms to use when searching medical literature.
This page is built from the MedlinePlus health topic record for Cold Sores, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.