Herpes and ingrown hairs can both cause painful blisters. Ingrown hairs cause painful bumps under the skin. Herpes causes blisters that can open and ooze.

More than half of adults in the United States have oral herpes, and 1 in 8 people between the ages of 14 and 49 years have genital herpes.

As many people shave the area around their genitals and other parts of the body that herpes may affect, it can be difficult to tell the difference between herpes and ingrown hair.

In this article, we examine the causes, symptoms, and treatment of both herpes and ingrown hair and explain how to tell them apart.

Typically, hair grows up and out of the hair follicle. Sometimes, though, the hair curls into the follicle, which causes it to grow under the skin. This downward growth can irritate the skin and cause inflammation that leads to the formation of red and painful blisters called pseudofolliculitis barbae.

Although anyone can develop ingrown hairs, they are more common in people who remove their hair, especially those who shave it.

In some people, ingrown hairs become so infected that they cause intense pain and even scarring. Sometimes, bacteria from other areas of the body get into ingrown hairs, causing painful infections that can cause fever and other signs of illness.

A person can usually prevent ingrown hairs by not removing body hair. Alternatively, the following hair removal practices may help reduce the risk of ingrown hairs:

  • exfoliating before hair removal
  • pulling the skin taut and shaving only in one direction
  • using a clean, sharp razor

Over-the-counter lotions may also reduce shaving-related irritation.

For more severe cases, a doctor may recommend retinoid cream to help the rash clear faster and steroids to relieve inflammation. When ingrown hairs become severely infected, a person might need oral antibiotics or an antibiotic cream.

Herpes is a common virus that a person gets through contact with herpes sores, which can occur if they kiss someone with oral herpes or have sex with someone with genital herpes.

The herpes virus lives in the body forever and occasionally reactivates, causing painful blisters that tend to break open and ooze.

While doctors often differentiate between oral herpes (HSV-1) and genital herpes (HSV-2), it is possible to spread oral herpes to the genitals, primarily through oral sex with an infected person who is having an outbreak.

For most people, the symptoms of herpes are mild, and after the first outbreak, subsequent outbreaks are less severe. However, in people with weakened immune systems and certain chronic illnesses, herpes may be more dangerous.

A pregnant woman may also be at risk of transmitting an active infection to the baby during vaginal delivery, so it is important for anyone who thinks that they might have herpes to get a proper diagnosis.

According to the Centers for Disease Control and Prevention (CDC), there is no cure for herpes. However, antiviral treatment can decrease the severity and frequency of outbreaks. It may also reduce the likelihood of a person spreading the virus to others.

Both herpes and ingrown hairs can cause painful red blisters, itching, and skin irritation.

If skin irritation is due to herpes, a person may experience:

  • sores that only appear on one side of the genitals
  • blisters that last 2–4 weeks
  • ulcers that appear 2–12 days after exposure
  • fever or flu-like symptoms
  • pain and other symptoms that occur before herpes blisters appear

It is more likely that an ingrown hair is responsible for a rash developing if a person has:

  • irritation that appears within 1–2 days of shaving or affects an area that has had exposure to a lot of friction
  • a visible hair growing just under the surface of the skin
  • risk factors for ingrown hairs, such as curly or tightly coiled hair

Some other types of skin rashes and blisters include:

  • Atopic dermatitis. This common type of eczema causes the skin to become itchy and inflamed. A person might notice red, itchy spots after using a new lotion, detergent, or shampoo.
  • A life threatening allergic reaction. A sudden rash that appears out of nowhere, spreads rapidly, or covers the entire body could indicate a severe allergic reaction. The person should go to the emergency room if they have other symptoms, especially if these include difficulty breathing.
  • Eczema. Other types of this chronic skin condition cause dry, flaky patches. Sometimes, these can resemble tiny blisters.
  • Cellulitis. Cellulitis is a severe bacterial infection in the deeper layers of the skin. A person with severely infected razor burn or ingrown hairs can get cellulitis. The affected skin is usually warm and red, and it may feel swollen. Cellulitis can spread quickly and may even become life threatening without prompt treatment.

A person should see a doctor if they have:

  • a first outbreak of herpes in the genitals
  • severe symptoms of a genital herpes outbreak, such as open sores around the genitals, anus, or thighs
  • symptoms of an ingrown hair that are very severe or do not go away on their own within a few days
  • a fever alongside a rash
  • a rash that is spreading rapidly
  • a rash and also have HIV or uncontrolled diabetes or are taking drugs that weaken the immune system

Parents or caregivers should take a baby or child who develops a rash to see a healthcare professional immediately. A pregnant woman who has a herpes outbreak close to her due date should also seek immediate medical care.

It is easy to panic about a sudden rash, especially when it is painful or itchy.

However, there is no reason to try to self-diagnose the issue. A doctor can quickly tell the difference between herpes and ingrown hairs and can recommend treatments that help with either.