# What are cold sores? Canonical page: https://clinicsjo.com/en/faq/ma-hi-quruh-al-bard Language: en Category: dermatology Publisher: ClinicsJo Published: 2026-09-13T08:09:51.249Z Content updated: 2026-09-13T08:09:51.249Z Translation (ar): https://clinicsjo.com/ar/faq/ma-hi-quruh-al-bard Cold sores, medically known as herpes labialis, are painful, fluid-filled blisters that typically form on the outside of the mouth, specifically on the lips or the area surrounding them. These sores are a very common condition, caused primarily by infection with the herpes simplex virus type 1 (HSV-1) [\[1\]](). After the initial infection, the virus remains dormant within the facial nerve cells, and many people may not experience any symptoms for years. However, the virus can reactivate at any time, traveling through the nerves to the skin, causing cold sores to appear in or near the same area [\[2\]](). It is essential not to confuse cold sores with canker sores; the latter appear exclusively inside the mouth (on the tongue, inner cheeks, or gums) and are not caused by the herpes virus, nor are they contagious [\[1\]]() [\[3\]](). ## Nature of the Infection and Viral Transmission Cold sores are highly contagious and are easily transmitted from person to person through direct contact, such as kissing, or by sharing personal items like eating utensils, cups, water bottles, or towels with someone during an active phase of the virus. Transmission can occur even in the absence of visible sores, although the likelihood of transmission increases when active blisters are present [\[2\]]() [\[3\]](). Extreme caution must be exercised to prevent the spread of the infection to sensitive areas; for instance, touching a cold sore and then touching the eye can lead to a viral eye infection, which is a serious condition that may cause corneal scarring or even blindness [\[1\]]() [\[2\]](). ## Warning Signs and Symptoms Cold sores are characterized by the appearance of warning signs in the affected area before the blisters themselves emerge. The process often begins with a feeling of tingling, itching, or burning around the lips. Subsequently, the condition develops into small blisters filled with clear or yellow fluid, and multiple blisters may merge to form a single larger mass. Over time, these blisters rupture to form a dry crust before healing completely, a process that typically takes between one and two weeks [\[2\]]() [\[3\]](). In cases of initial infection, the patient may experience general symptoms similar to a viral infection, such as fever, general fatigue, swollen lymph nodes, or difficulty swallowing [\[1\]]() [\[2\]](). ## Triggers for Cold Sores Once infected with the virus, several environmental and physical factors can trigger its reactivation, leading to the appearance of blisters. These triggers include hormonal changes (such as menstruation), excessive exposure to sunlight, extreme emotional or physical stress, and illnesses that cause fever. Therefore, it is often recommended to use lip balms that contain sun protection to reduce the risk of activation caused by ultraviolet rays [\[1\]]() [\[2\]](). ## When Should You See a Doctor? Although cold sores usually heal on their own, medical intervention becomes necessary in certain cases. It is advisable to consult a doctor if the sores do not heal after two weeks, or if they are severe and painful to the point of hindering eating and drinking. Medical attention should be sought immediately if blisters appear near the eyes, if the person has a weakened immune system, or if the sores recur frequently and distressingly, as the doctor may prescribe antiviral medications to reduce the severity of symptoms and accelerate healing [\[1\]]() [\[2\]](). You can read more about care measures in [Cold Sores (Oral Ulcers): Causes, Treatment, and Infection Prevention (Arabic)](). ## Medical references - [Fever Blisters & Canker Sores]() - [Herpes - oral]() - [Cold Sores]() General health education; not a substitute for individualized clinical assessment. Citation URL: https://clinicsjo.com/en/faq/ma-hi-quruh-al-bard#answer