Please ensure Javascript is enabled for purposes of website accessibility

Cold sores, also known as fever blisters, are an inconvenient annoyance for most people, but easily managed. But cold sores can spell trouble for people with weakened immune systems. Though the sores themselves are a minor irritation, the symptoms of the cold sore virus can also appear elsewhere in the body if your immune system is compromised. Your physician will alert you if your medical condition or treatment is likely to weaken your immune system and if fever blisters are more than pesky sores.

Why Are Cold Sores Bad?

For most of the population, cold sores aren’t a serious problem. Many people carry the herpes simplex virus type 1 (HSV-1), which causes clusters of tiny, fluid-filled blisters to appear on or near the lips. For most carriers of the virus, cold sores are the only symptoms they experience, and the blisters usually crust over and disappear in about a week.

If you have a weakened immune system, however, the story isn’t so simple. As the Mayo Clinic explains, a weak immune response may not control the virus at the cold sore stage, and symptoms may spread to the fingertips, eyes, skin and organs, like the brain or spinal cord.

Who Is at Risk From Cold Sores?

HSV-1 carriers are at risk of complications from cold sores if they have medical conditions or are undergoing treatments that suppress the immune system, notes the Mayo Clinic. Patients who take anti-rejection drugs after an organ transplant or are receiving chemotherapy to treat cancer have weakened immune systems, and for them, a cold sore could turn into something more serious. Similarly, people with immunosuppressive conditions like severe burn sufferers and people infected with HIV should monitor their health closely if they notice a cold sore appear. Eczema sufferers are another at-risk category of patients.

Cold Sore Treatments

Symptoms of a cold sore outbreak often appear before the sores themselves, and you can try to stop the virus in its tracks at this early stage with a range of treatments. If you feel a tingling, burning sensation or see redness or swelling around your lips, ask your physician or dentist about antiviral drugs, like famciclovir, acyclovir and valacyclovir, which may prevent cold sores from appearing. Or you can visit the dentist and see if they can treat the cold sore with laser therapy.

Once the cold sore is there, you can treat it with over-the-counter ointments or hold a cold compress to the area to help the sore heal quickly. To soothe cold sore irritation, apply a maximum-strength oral pain reliever for canker and mouth sores. Remember to wash your hands with soap and hot water before and after touching a cold sore to help prevent secondary infections and reduce the spread of the virus.

When Is a Cold Sore Serious?

Without treatment, a cold sore should disappear within 10 to 14 days. If your immune system is weak, you should contact your physician if you develop a cold sore. Additionally, talk to your family doctor if you’ve had a cold sore for longer than two weeks and have symptoms like fever, rash, drooling, difficulty swallowing, or white patches on your tongue and roof of your mouth.

Are cold sores bad for you? A simple sore isn’t a problem by itself, but if the virus that caused it shows up elsewhere in your body, you could become ill. If you think you have a weakened immune system and you feel that familiar tingling that signals a cold sore’s appearance, heed the advice of your doctor on the best course of action.