Viral Infections in the Mouth (Symptoms with Pictures)

Your mouth is a common gateway for many viruses and bacteria.

Some viral infections can settle directly in the mouth and cause noticeable symptoms. Two of the most common examples are the herpes virus, which causes cold sores (also known as fever blisters), and human papillomaviruses (HPVs), which can lead to benign tumors commonly known as warts.

In this article, we’ll take a closer look at the different types of viral infections that can affect your mouth and the symptoms to watch out for.

1. Herpes virus infection: Cold sores

Herpes virus infections are well-known for causing mouth ulcers called cold sores or fever blisters.

About 3.7 billion people under age 50 (around 67% of the world’s population!) carry herpes simplex virus type 1 (HSV-1), which is the main type involved in oral herpes.

Most of the time, the virus stays dormant and causes no symptoms, so you may not even know you have it.

However, certain triggers — like an injury, stress, illness, hormonal changes, or sun exposure — can reactivate the virus and cause a herpes outbreak. Cold sores appear as small, fluid-filled blisters, usually on or around the lips.

Cold sores are highly contagious and can be transmitted through direct contact with the blisters or with the affected area.

2. Varicella-Zoster Virus Infections:

Varicella-zoster virus (VZV) infections are also common. Over 95% of people carry the dormant form of VZV. In the United States, around 1 in 3 people will develop a recurrent infection (mostly older adults).

The infection has two stages:

The first stage is called chickenpox, which occurs when you get the virus for the first time — typically in childhood. It causes itchy, fluid-filled blisters that cover the entire body. Chickenpox spreads mainly through respiratory droplets from an infected person or direct contact with fluid from their blisters.

After this stage, the virus goes dormant in the body’s nerves.

The second stage is called herpes zoster, or shingles, which can occur later in life, especially in older adults. Why? Because the immune system weakens with age, which allows the dormant virus to reactivate and cause an outbreak.

Shingles leads to a painful rash that can appear anywhere on the body, including inside the mouth. What sets shingles apart is that the sores affect only one side (right or left), while the other side remains unaffected (as shown in the image above).

3. Human Papillomavirus Infection (HPV):

Human papillomavirus (HPV) infection is caused by the human papillomavirus, which is very common and can affect both men and women. It’s mainly spread through direct contact (especially sexual contact).

There are more than 200 types of HPV, but not all of them cause symptoms in the mouth. HPV types 2 and 4 are the most well-known for affecting the mouth.

When these viruses settle on the skin or the lining of the mouth, they affect the outer cells and cause benign growths known as warts.

These infections are usually harmless and are easily controlled by a healthy immune system.

However, some types of HPV are more serious and carry a higher risk of cancer — especially HPV-16.

4. Coxsackie viral infection (Hand, foot, and mouth disease):

Coxsackie viral infection, better known as hand, foot, and mouth disease (HFMD), is a highly contagious viral illness caused by the Coxsackie virus. It mostly affects children under the age of 5 but can sometimes occur in adults too.

HFMD spreads mainly through close contact with someone who is infected. This includes respiratory droplets from coughing or sneezing, contact with blister fluid or saliva, and touching contaminated surfaces or objects.

The disease gets its name from its most common symptoms: a rash or sores on the hands, feet, and inside the mouth.

5. HIV (human immunodeficiency virus):

HIV, short for human immunodeficiency virus, is a virus that attacks your body's immune system. Specifically, it targets a type of immune cells known as CD4 cells or T-helper cells, which are essential for fighting off infections and diseases.

When HIV weakens your immune system, it makes you more vulnerable to various illnesses and infections.

If left untreated, HIV can progress to a more advanced stage known as AIDS (acquired immunodeficiency syndrome).

Among the body parts to show the first signs are the face and mouth. In fact, 50% of HIV-infected patients and up to 80% of patients in the AIDS stage have oral manifestations of the virus.

HIV Transmission:

HIV is transmitted mainly through unprotected sexual contact.

The virus does not spread through skin contact. To contract the virus, the body fluids (such as blood, semen, and vaginal secretions) you come into contact with must contain a high viral load. Plus, they have to enter your bloodstream through a wound or mucus membranes (such as the inner lining of your mouth).

Casual contact or skin exposure alone does not put you at risk of HIV transmission.

How long before HIV shows symptoms?

When you first contract the virus, signs don’t appear immediately. Initial symptoms may take several weeks to show up and often resemble those of the flu.
After this initial phase, HIV may cause no symptoms for years, quietly multiplying within the body.
Later, the virus can progress and lead to the AIDS stage.