How long after a cold sore can you give oral sex?

You may have planned a special night with your partner, and you expected to get intimate. But after looking in the mirror, you realise you’ve got a cold sore.

Cold sores can be incredibly irritating and painful, but they can also be distressing because of the risk of spreading them to someone else.

This blog will review what causes cold sores, how contagious they are, and when you can be intimate with someone after an outbreak.

If you think you may have Herpes, get tested at home with one of Better2Know’s Home Test Kits.

What causes cold sores?

Cold sores – sometimes called fever blisters – are small red blisters that develop around the lips and mouth. They are usually caused by Herpes Simplex Virus Type 1, or HSV 1 (often known as Oral Herpes). An HSV 1 infection is permanent, and someone infected with the virus will live with it for the rest of their life.

Someone already infected with HSV 1 may not experience any symptoms. But when you become infected for the first time symptoms do occur, usually arrive 2 to 12 days after the initial infection. We call this primary Herpes.

During the initial stage of primary Herpes, the infected person may experience a burning, swelling, or itching sensation around the site of the impending outbreak. Next, small blisters filled with fluid will appear around the mouth – either a single blister or in clusters. These blisters will eventually burst and turn into painful sores, which will heal over. Other symptoms may accompany the appearance of blisters, such as fever, muscle aches, and headaches.

The first Herpes virus outbreak is usually the most severe. After the initial infection, the virus lies dormant in a cluster of nerve cells called the trigeminal ganglia located in and around the face and head. The virus may periodically travel to the skin, causing recurrent outbreaks.

External factors like sunlight exposure, stress, and changes in the weather can trigger outbreaks of cold sores. However, external stimuli aren’t needed – the virus can travel from the nerves to the skin on its own.

While HSV 1 is the primary cause of cold sores, they can also be caused by Herpes Simplex Virus Type 2, or HSV 2. HSV 2 is the virus that causes Genital Herpes infections but can also cause cold sores around the mouth if the virus is transmitted orally. Unfortunately, it’s not possible to tell whether cold sores are caused by HSV 1 or HSV 2 without getting tested.

How do cold sores spread?

HSV 1 tends to spread through skin-to-skin contact, like kissing. People with HSV 1 are very contagious during an outbreak. Simply touching cold sores during an outbreak can spread the virus.

However, you cannot pass on your Herpes if you’re kissing someone who has also had the same Herpes strain in the past. They will be completely immune.

It is also possible to pass on HSV 1 without an outbreak through an uncommon process known as “asymptomatic shedding”, where the virus travels to the skin but does not cause a blister.

While HSV 1 is usually contracted through kissing, it is possible to transmit HSV 1 to your partner’s genitals through oral sex. It is also possible to contract HSV 1 by performing oral sex on someone with a genital HSV 1 infection. Again, it is important to remember that this is absolutely impossible if your partner has ever had Herpes Type 1 in the past.

How long after a cold sore are you contagious?

While you will technically always be contagious if you have HSV 1, the likelihood of spreading the virus will be near zero when your cold sore has healed. After the blisters burst, a cold sore usually takes around two to three weeks to heal.

How often do Herpes outbreaks recur?

There are no hard and fast rules for when a Herpes outbreak will occur. Some people who contract HSV 1 never get an outbreak. Others will only get a single outbreak, while others will have many outbreaks over time.

In general, people who have recurrent genital Herpes outbreaks average about four a year, although this will be different from person to person, and Herpes Type 2 is much less common. One person may get ten outbreaks a year; another may get two. There is no way to predict the frequency or severity of outbreaks.

Is it ever safe to perform oral sex if you have cold sores?

If you have a cold sore, you are more likely to spread Herpes to your sexual partner.

If you are experiencing an outbreak, you should avoid kissing and any sexual contact (including oral sex) until the cold sore has healed. You should also avoid touching your sore and then touching other people, or allowing other people to touch your sore.

But as we mentioned earlier, it’s entirely safe to be in contact with someone who has also had the same Herpes virus. You will not infect them.

Final thoughts

Cold sores can be incredibly irritating, but Herpes outbreaks can be managed with the right treatment.

If you think you may have a Herpes infection, you should get tested as soon as possible.

Call the number above to speak to one of Better2Know’s Sexual Health Advisors.

Don’t leave your sexual health to chance.

This article was medically reviewed by Dr. Steve Chapman, 29/08/2025.

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