Healthy Living

How Are Cold Sores Diagnosed?

You might be able to diagnose cold sores yourself, just by looking at them. But here's how the diagnosis works.

How Are Cold Sores Diagnosed?

A cold sore is a common viral infection which is caused by Herpes Simplex Virus or HSV. HSV is quite commonly present in all our blood streams and wakes up when our immune system gets suppressed or weak. So often when one has fever or cold, they can observe small, fluid-filled blisters, usually in a small cluster, on and around the mouth area, which is nothing but cold sore. These cold sores can multiply if one regularly or picks the lip area which is affected or touches other areas of the body like inner nose or genitals. This, in turn, means that cold sores can spread through one to one contact with another person, as in the case of kissing or even sharing items like lipstick or towel, previously used by a person who has HSV.

The area where the cold sore is likely to appear will initially itch. Eventually, blisters appear and take around two to four weeks to heal completely on its own. These blisters can be a bit painful when they break and one might find it difficult to eat properly if there is a cold sore on the mouth. After around ten days the blisters will form a crust or yellow scab which dries and falls eventually. Usually, the blisters do not leave any scars after healing.

When can a cold sore generally appear?

A cold sore can be seen when one is experiencing symptoms such as tingling or itching, blisters, swelling, fever, sore throat, swollen lymph nodes in the neck, pain in the mouth and swollen gums, muscle aches, hormonal imbalance during menstrual periods and headache. These symptoms vary, depending if it is the first outbreak or recurrence. Cold sore recurrences usually appear at the same spot and are less severe compared to the first outbreak.

Antiviral medications and creams help in reducing the severity of the symptoms and help speed up the healing process. Keeping an ice pack over the cold sore, without pressing hard on the blisters can relieve the pain caused by the cold sore for some time.

When to see a physician?

It is best to see a doctor if:

  • The cold sore doesn’t heal in two weeks
  • You’re experiencing severe symptoms
  • Your immune system is suppressed or you are feeling too tired
  • The cold sores are recurring frequently
  • You can see pus along with the fluid in the blister
  • Cold sores are accompanied by eye irritation or redness in the eye
  • You develop cold sores during your pregnancy

Cold sores – Diagnosis

Cold sores are not dangerous to our body and their diagnosis is pretty easy due to their recognizable features. Identifying symptoms such as tingling and itching followed by blisters around the mouth (or nose) are enough for the physician to recognize that it is a cold sore. Though tests are not required to confirm the same, depending on the severity of the cold sore, doctors may take a sample of the blister fluid to reconfirm the diagnosis.

If the diagnosis is questionable, there are a variety of tests available such as polymerase chain reaction (PCR) and viral culture test. These tests are performed by rubbing a swab over an active blister. The swab will then be sent to the laboratory for culturing. The culture could last from 24 to 48 hours. The swab that has been rubbed over the sore can also be used to test for herpes DNA. This can be done through polymerase chain reaction. It is very reliable in detecting herpes but is not readily available. Blood tests help in detecting the presence of antibodies in the blood. These antibodies are produced by the body to fight herpes simplex virus.

The tests are commonly prescribed for people with a weak immune system such as people with AIDS or HIV and cancer patients undergoing chemotherapy.


A cold sore is contagious. Thus, it is important to learn ways where a carrier can prevent the spread of infection to other people.

The following steps are helpful to avoid the spread of cold sores to other parts of the body and to other people:

  • Keep your hands clean; wash them regularly.
  • Avoid skin to skin contact.
  • Do not share personal things or items such as towels, utensils, and lip balm.
  • Apply a sun block if sunlight triggers your cold sore outbreak.
  • Do not make close contact with babies and people with weakened immune system.
  • Avoiding touching your eye area or other body parts, in case you touch an active cold sore and wash your hands immediately.
  • Always dab the antiviral creams on the blisters and do not rub them, as there are high chances of spreading.
  • Do not let dust accumulate on or the area surrounding the cold sore. Always try to be clean.
  • Cold sores caused by stress can be reduced by adopting techniques like breathing exercises or meditation, which relaxes the body.
  • Maintain a healthy lifestyle by eating a balanced diet and exercise regularly to strengthen the body immune system.

Problems due to untreated cold sores

Though cold sore can be treated with no much hassle, people with weak immune system can face further problems such as:

  • Dehydration is the most common problem due to lack of water intake, considering the pain caused by the cold sore on the lips.
  • Skin condition like eczema, where the skin becomes itchy, red and dry when the cold sore comes in contact with bruised or broken skin.
  • Eye infections which can be less severe as in inflammation of the eyelids to infection in the cornea which in extreme conditions may lead to blindness.
  • Very rare cases of swelling and inflammation of the brain called encephalitis can occur, if the cold sore virus spreads to the brain.

Thus, a cold sore is not a lifelong issue. With early detection and proper treatments, it can be cured easily. But, not falling sick frequently and understanding our body needs is in our hands. A few simple lifestyle changes in terms of eating right, maintaining hygiene and keeping our body calm and go a long way in keeping the cold sores away.