Sores on Lips (Cracks, Blisters, Lumps) Causes

As with any part of the body, sores may arise on the lips for a number of different reasons. It is usually temporary but sometimes lip sores may recur and be linked to serious diseases. It may be accompanied by swelling of the lips, pain and tenderness. In severe cases there may even be bleeding and hypersensitivity of the lips. Understanding the causes of these lip sores is important in identifying ways to prevent and manage it.

What is a Lip Sore?

A lip sore is any lesions like a blister, ulcer, scab, pimple or other type of abnormality that develops on the lip. It can occur for a number of different reasons. These sores can affect any person since the lips are prone to injury as it is thinner than the skin around it. Sometimes lip sores are related to infections, allergies or more serious conditions and can persist for long periods of time or recur (goes away and then comes back again).

As with most sores, it is usually not serious and resolves on its own within a short period of time. However, it can be a cosmetic concern and sometimes even affect daily activities like eating due to pain and tenderness. The occasional sore that is related to trauma is a not a cause for concern and the precipitating factor should be avoided in the future. However, persistent or recurrent sores should always be investigated further.

chapped lips

Causes of Lip Sores

Some of the more common causes of lip sores has been discussed in detail below. Many of the causes of lip sores are acute and occurs with injury and irritation to the lips. It lasts for short periods of time and resolves with proper care. Sometimes lip sores can be due to chronic diseases and more serious conditions. The lesions may ease once the underlying condition is properly treated and managed.


Injury to the lips is a common cause of sores. It may occur through various ways such as biting the lips, consuming very hot foods or beverages, picking at the skin on the lips and ill-fitting dentures or braces. Even vigorous brushing or flossing can also cause trauma to the lips. This injures the delicate skin over the lips and if it bleeds a scab may form. Injuries also increase the risk of infections on the lips.

Dry Lips

The lips can dry very easily and this in turn can make it prone to injury, infections and other diseases that may lead to sores. In dry and windy climates, the lips are one of the first surface areas to dry. The movement of air across the lips with mouth breathing can also lead to dryness. Repeatedly licking the lips may also hasten drying as well dehydration that leads to dryness in and on many areas of the body.


Although saliva is a normal secretion within the mouth and makes regular contact with the lips, it can also pose a problem to the lip tissue. Saliva on the lips hastens drying of the lips although most of us lick our lips as a short term measure to counteract dryness. In doing so, we ultimately worsen dryness. Saliva on the lips for long periods can also act as an irritant and lead disturbances in the skin which may progress further to the development of sores.


Lip cosmetics like lipstick can also cause lips sores in some people. It depends on individual sensitivity. The substances can cause irritation of the skin on the lips. This is known as irritant contact dermatitis. In some hypersensitive individuals these substances can trigger an allergic reaction and is known as allergic contact dermatitis.


There are a number of different infections that can cause lip sores which may be due to viruses, bacteria or in rare cases by yeasts. The most prominent of these is a cold sore or fever blister. It is caused by the herpes simplex virus type 1 (HSV-1) and is easily spread from one person to another during close contact like kissing. Genital herpes (HSV-2) can also cause lip sores in some cases.


The skin on the lips is just as prone to sun damage as skin elsewhere on the body. This may not always present as sunburn and therefore sun damage is not always noticed. Sunburn is an acute inflammatory reaction to intense UV (ultraviolet) light exposure. Sunlight is the most common source but it can also occur when using tanning booths and in some cases there may be industrial exposure from other artificial sources.

Skin Diseases

There are a number of skin diseases that can affect the lips, apart from contact dermatitis. Some of these conditions are related to allergies, autoimmune conditions, infections and other causes of inflammation that are not always identifiable. Atopic dermatitis commonly referred to as eczema and psoriasis are common skin diseases that may in some cases also extend to the lips.

Angular Cheilitis

Cracking and sores at the corner of the mouth is known as angular cheilitis. It is an inflammatory condition that is caused by trauma, skin diseases and infections. It may also be linked to nutritional deficiencies, celiac disease, inflammatory bowel disease and with certain drugs. In severe cases there may be bleeding from the corners of the mouth and can lead to darkening of the skin in the area.

Nutritional Deficiencies

Nutritional deficiencies have also been linked to lip lesions. It is mainly seen with deficiencies of iron and the B-vitamins. With regards to the latter, it is seen more prominently with vitamin B12 deficiency, folate (vitamin B9) deficiency and riboflavin (vitamin B2) deficiency. It can occur with poor nutrition, starvation, extreme dieting and fasting for long periods of time.


Certain drugs can cause lesions on the lips and this is mainly seen with the use of isotretinoin. This drug is widely used for treating acne and also used in the treatment of other conditions like psoriasis. A similar type of drug known as acitretin is also known to sometimes cause skin lesions. Acitretin is a retinoid like isotretinoin and is mainly used for treating psoriasis.

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