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Doctor insights on: How Long Is A Fever Blister Contagious

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My 9 year old keeps getting fever blisters. Why? Are they contagious?

My 9 year old keeps getting fever blisters. Why? Are they contagious?

Yes: Fever blisters/cold sores are most commonly caused by the hsv1 virus which is very common and found in most people. The virus is contagious and some people are simply more prone to getting the "fever blisters" than others. There are some meds, including topicals that help decrease the duration of the symptoms and provide some relief. Best wishes. ...Read more

Dr. Philip Miller
1,735 Doctors shared insights

Blistering (Definition)

A blister is a collection of fluid under the epidermis. A blistering rash is one in which ...Read more


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2 yr old has HFMD. Started fri/sat. When will he stop being contagious? Fever gone, still has blisters on Wed. Ok for family event Saturday?

Hard to say: At 2, their general activities include mouthing toys and fingers and spreading saliva around their environment. Since HFV viruses can shed in the respiratory tract and saliva for 1-2 weeks after initial symptoms, so how and when they stop spreading the germ is difficult to say. It can persist for 4-6 weeks in the stool. ...Read more

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My bestfriend's bf gets lip blisters ever since he was a kid. He got them last in 2012 due to sun exposure, this time after a fever. Is it contagious?

My bestfriend's bf gets lip blisters ever since he was a kid. He got them last in 2012 due to sun exposure, this time after a fever. Is it contagious?

Cold blisters: Herpesviruses at the edge of the lip are contagious, so much so that most people your age are already infected. Stress, illness and sun exposure can cause a new breakout. ...Read more

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7 hrs after fainting and vomiting, fever blisters appered on my chin. Can this still be related to my episode? Or herpes? And is this contagious?

Stress: "fever blisters" are caused by herpes simplex and are contagious. We are all exposed to herpes simplex at a young age. Some people continue to have outbreaks during stressful times and with exposure to the sun. Others may never have repeated outbreaks. Your body was stressed due to the vomiting and fainting episode you had. Thus, the outbreak of herpes simplex.

Valtrex will treat this. ...Read more

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If a fever blister on the roof of the mouth is gone, but the area is still tender is it still contagious?

If a fever blister on the roof of the mouth is gone, but the area is still tender is it still contagious?

Probably not: If no blister or vesicle is there, you are probably feeling the after effects of the lesion which should fade with time. ...Read more

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If a child has Hand, Foot, Mouth Disease and has blisters that are still erupting, but no fever. Is he or she contagious or no?

If a child has Hand, Foot, Mouth Disease and has blisters that are still erupting, but no fever. Is he or she contagious or no?

Hand/foot/mouth: Generally, a person with hand, foot, and mouth disease is most contagious during the first week of illness. People can sometimes be contagious for days or weeks after symptoms go away. This is why people should always try to maintain good hygiene (e.g. handwashing) so they can minimize their chance of spreading or getting infections. ...Read more

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My mother in law just had some dental work done and now she has a fever blister on her lip. Does this mean she has hsv-1 and is contagious?

My mother in law just had some dental work done and now she has a fever blister on her lip. Does this mean she has hsv-1 and is contagious?

Perhaps: If she had a previous history of hsv, then the stress of dental work can lead to a localized breakout. If it is hsv, then yes, she is contagious. Anytime there are active hsv lesions - oral or genital - then one is contagious. It's the fluid within the blister that contains the virus. ...Read more

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How long is a fever contagious? I had 102 last night and now I have 99. I work with children...Is taking a rest day a good idea

How long is a fever contagious? I had 102 last night and now I have 99. I work with children...Is taking a rest day a good idea

Yes: Most viral illnesses are likely spreading live virus in the saliva and respiratory secretions for up to 24 hours after the fever stops. Good hand washing and wearing a mask can contain most of the spread, but a 24 hour period fever free is considered the best way to stop spread. If the issue were something like strep throat, treatment would need to be underway for 24 hrs before it was contained. ...Read more

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How long is a fever present  before blisters appear with hand, foot, mouth disease?

How long is a fever present  before blisters appear with hand, foot, mouth disease?

Hand, Foot & Mouth: Hand, foot, and mouth disease usually starts with a fever, poor appetite, a vague feeling of being unwell (malaise), and sore throat. One or 2 days after fever starts, painful sores usually develop in the mouth (herpangina). They begin as small red spots that blister and that often become ulcers. The sores are often in the back of the mouth. A skin rash develops over 1 to 2 days. ...Read more

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What causes typhoid fever, and how long is one contagious?

What causes typhoid fever, and how long is one contagious?

Bacteria: Typhoid is caused by a bacteria called salmonella typhi. It is common in under developed countries where clean potable water and good sewage systems are not available. Most us cases occur in those who have traveled and been exposed to contaminated food or water. Infected people excrete the bacteria in their stools for up to 3 months, so they are contagious until the diarrhea resolves. ...Read more

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If I have a fever and am breastfeeding, how long am I contagious?

If I have a fever and am breastfeeding, how long am I contagious?

Depends on cause: Fevers caused by infectious diseases are usually contagious 24 hours after the end of fever, or 24 hours after the start of antibiotics if caused by a bacterial infection. However, not all fever is caused by infections. You can have other reasons for running a fever such as autoimmune diseases. And an illness doesn't mean you need to stop breastfeeding - it can protect your baby to breast feed. ...Read more

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How long is the flu contagious after fever has broken and aches are gone?

See below: Virus sheding in influenza begins 1 day before the start of symptoms and then continues for about 8 days after the start of symptoms. This would be the time that patients are contageous. ...Read more

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How long after I have had the flu after my fever has broken am I contagious?

How long after I have had the flu after my fever has broken am I contagious?

Let me help: The period when an infected person is contagious depends on the age and health of the person. Studies show that most healthy adults may be able to infect others from 1 day prior to becoming sick and for 5 days after they first develop symptoms. Some young children with weakened immune systems may be contagious for longer than a week. ...Read more

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How long can a oral medication for fever blisters leave and help inside your body?

How long can a oral medication for fever blisters leave and help inside your body?

Not sure: Fever blisters or hsv I viral outbreaks can be shortened by immediate use of zovirax, (acyclovir) but if not taken before 48 or so hours into it, it will be of little benefit. I do not know the specific body clearance for the drug, but as it is dosed every 4 hours, I imagine it is cleared rapidly. Medication most helpful if you feel an outbreak coming on, waiting only reduces effectiveness. Good luck! ...Read more

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Think my son has HFM. Never had a fever. Already scabbed up. A few blisters still. Going on day 6. How long will it last?

Think my son has HFM. Never had a fever. Already scabbed up. A few blisters still. Going on day 6. How long will it last?

Self limited.: HFM usually last a week to 10 days. Treatment is symptomatic with acetaminophen or possibly age appropriate ibuprofen and keep child hydrated. Should not last much longer but other children in household may get it.
...Read more

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I started tamiflu (oseltamivir) 2 days, almost 3 days ago and I have no fever for 24 hours and I feel fine. Am I still contagious? If so, how long?

I started tamiflu (oseltamivir) 2 days, almost 3 days ago and I have no fever for 24 hours and I feel fine. Am I still contagious? If so, how long?

Up to 7 days: The shedding of the virus in your secretions peaks in the first 3 days of the illness but persists up to 7 days regardless of the use of tamiflu (oseltamivir). While the shedding diminishes as the fever drops, it can persist and the need for isolation depends on the situation. ...Read more

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How long are you contagious after a fever?

How long are you contagious after a fever?

Fever: Contagion, or the ability to transmit your illness to others, depends upon the causative organism and the duration of fever may or may not have any relationship to communicability. If we knew what illness you had, could answer this more specifically. ...Read more

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Hi! My 6 yr old was dx with HFM tonight. How long is she considered contagious? Until 24hrs fever-free?

Hi! My 6 yr old was dx with HFM tonight. How long is she considered contagious? Until 24hrs fever-free?

HFM: Did the doctor tell you what the initials stood for? They can mean different things. Let us know so we can answer your question. All the best. ...Read more

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How easy is it to spread glandular fever, and for how long is it contagious?

How easy is it to spread glandular fever, and for how long is it contagious?

Mononucleosis: It is quite contagious. You are contageous when you are actively ill and can remain contagious for a number of months later. ...Read more

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What would you do to get rid of a fever blister faster how long will it take?

What would you do to get rid of a fever blister faster how long will it take?

Cut time in 1/2: Melissa officinalis or lemon balm (cream) has been shown in european studies to help expedite healing of cold sores. It can reduce healing time by half. Studies also show that regular use can help v recurrences. Brief supplementation with lysine 1, 000mg orally three times a day at the onset, can also hasten healing. Your physician can prescribe valtrex (valacyclovir). Can take up to a week. Can cut time in 1/2. ...Read more

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Tested positive to glandular fever likely got it 3 mths ago. How long would I still be contagious for? Would my kids & husband be ok?

Tested positive to glandular fever likely got it 3 mths ago. How long would I still be contagious for? Would my kids & husband be ok?

Maybe lifetime: You may shed the Epstein-Barr virus in your saliva on and off for the rest of your life. No big deal. EBV doesn't seem to be harmful to kids. Kissing is healthy; your husband has met the virus too and won't be harmed. Don't be afraid of viruses that most people have, and be thankful for family love. ...Read more

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How long is croup contagious? My son drank out nieces cup who had it last wk. Her fever is gone and she's back at school. Still has a cough. Worry?

How long is croup contagious? My son drank out nieces cup who had it last wk. Her fever is gone and she's back at school. Still has a cough. Worry?

Unlikely...: Though one may contract a virus by touching a contaminated surface and then touching the eyes, nose or mouth, the timing of your niece's illness makes it unlikely. Croup is usually caused by a virus infection, most often a parainfluenza virus. After the third day of symptoms, a patient will begin to clinically improve. The cough may in itself represent a post-viral cough that may persist for weeks. ...Read more

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How long after my fever breaks am I still contagious?

How long after my fever breaks am I still contagious?

Too little informati: The pathogen responsible for the fever is not specified, so there is no reasonable answer one can give. Try again with more information, good luck! ...Read more

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My son started having symptoms of croup 48 hours ago. He was diagnosed by a Dr. Today. His fever is gone now. How much longer will he be contagious?

My son started having symptoms of croup 48 hours ago. He was diagnosed by a Dr. Today. His fever is gone now. How much longer will he be contagious?

Shedding for awhile: Viral shedding, or period of contagiousness, for these types of viruses can last weeks, and are shed through the upper respiratory structures. However, since most of the shedding occurs during the time that the person is feeling very sick and febrile, let your son's behavior and overall appearance be your guide. Most daycares and schools require a 24 hour fever free period (without medications). ...Read more

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How long after fever breaks am I still contagious? (Should I go on car ride with friends if for sure fever free for 12 hours)

Generally, 24 hours: The period of contagiousness is variable depending on what sort of infection you have, but in general it is recommended to stay home from school, work and daycare until you are fever free for 24 hours without acetaminophen or ibuprofen. ...Read more

Contagious (Definition)

One is able to transmit an infection to another by ...Read more


Dr. Mark Diamond
2,227 Doctors shared insights

Fever (Definition)

Fever = elevated body temperature (can be ...Read more