Can Stress Trigger A Cold Sore Outbreak?

Cold sores are painful blisters on the lips that often ooze and scab. They are caused by the herpes simplex viruses — typically herpes simplex type 1 (HSV-1). Herpes simplex type 2 (HSV-2) can also cause cold sores.¹

Around half of the US population is estimated to have the herpes simplex virus.² The virus can become more active when triggered. Cold or hot weather, a weakened immune system, diet, fatigue, injury, hormonal changes, and stress can trigger cold sores.

Managing your stress levels is a helpful approach to preventing outbreaks. Let’s explore the link between cold sores and stress.

Have you considered clinical trials for Cold sores?

We make it easy for you to participate in a clinical trial for Cold sores, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

Cold sores: symptoms and causes

Cold sores can develop when you are exposed to HSV-1 or HSV-2.³ They are clusters of small, weepy blisters that develop around the mouth or genital areas.

The virus thrives in warm environments. It’s highly contagious during the blister phase and is spread through skin-to-skin contact. It’s best to avoid kissing and wash your hands regularly during an outbreak.

Seeing your first cold sore appear a few days after exposure is normal. You might notice a slight tingling in the skin where the blister is forming. Then you will feel a bump. A blister will form next, followed by some oozing for a day or two. Your immune system will then kick in, and scabs will form over the blisters while new skin grows and covers the affected area.⁴

The cold sore is contagious until the scab falls off, so it’s best to wait for a few days before resuming activities that could spread the virus.⁵

How stress affects your health

Feeling stressed? You’re not alone. 67% of adults in the US report their stress levels have risen since the COVID-19 pandemic.⁶ So, while feeling stressed isn’t uncommon, it can harm your physical and mental health.

Stress triggers your body’s “fight or flight” response. You switch from long-term to short-term survival mode as if you are running away from a predator. Your brain, heart, and muscles go into overdrive to overcome the perceived threat. When this response is repeated over a prolonged period, you’ll eventually develop problems with your immune, reproductive, digestive, and other bodily systems.⁷

Stress releases adrenaline and cortisol into your system.⁸ Hormone overload makes turning your brain off at night challenging, leading to insomnia — a common sleep disorder.

What’s the link between stress and cold sores?

Your immune system works to prevent HSV from causing cold sores.⁹ However, long-term stress is known to have a detrimental effect on the immune system, making it much more likely that cold sores develop.¹⁰

A team at the UNC School of Medicine found that when the body releases stress hormones, the neuron pathway in the brain that blocks HSV from reactivating opens up. This clears the way for the virus to replicate.¹¹

Cold sore triggers

Stress isn’t the only thing that triggers cold sores. Here are some other factors that can lead to an outbreak:¹²


Having chapped and cracked lips from extreme heat or cold, or even wind, can cause the skin around your mouth and lips to become a welcoming environment for the virus. Applying lip balm with an SPF if you’re often outside in extreme weather conditions can help prevent cold sores.

Weakened immune system

If you have another infection, your immune system is weaker than usual. You may be more susceptible to a cold sore flare-up.¹³ A fever can also compromise your immune system and lead to a cold sore.


Arginine, an amino acid found in nuts, seeds, and red meat, can boost the reproduction of HSV. This increases your risk of developing a cold sore.¹⁴

Lysine — another amino acid — is an antagonist to arginine, so it’s commonly used to prevent and treat cold sores. Remember the importance of balanced nutrition, especially when you feel stressed.

Fatigue or injury

Your body can’t fight off viruses as effectively when you’re tired because your immune responses are not strong enough.¹⁵

An injury to your mouth can also lead to a cold sore, especially if there’s an open wound near your lips.¹⁶

Hormonal changes

Some women report an increase in genital herpes (usually caused by HSV-2) outbreaks during their period. As such, experts may assume that cold sore flare-ups may be related to the hormonal cycle. This association needs to be confirmed, but it may be a good idea to observe if your hormonal changes trigger cold sore outbreaks.

Managing stress is key

You can try the following strategies for managing stress in your life:¹⁷

  • Eating a healthy diet

  • Keeping active

  • Getting plenty of sleep

  • Practicing relaxation techniques like yoga and meditation¹⁸

  • Talking to a counselor or support group

These and other forms of self-care may help you manage or prevent stress, reducing your risk of developing stress-induced cold sores.¹⁹

Treating cold sores

Cold sores typically clear up on their own after a few weeks. Not everyone needs treatment, but some treatments can help the sores heal faster, reduce the risk of recurrence, and prevent the virus from spreading.

The best time to treat a cold sore is before it blisters. Over-the-counter creams and patches won’t necessarily stop it altogether, but they can inhibit the growth of the virus and stop the outbreak from becoming aggressive.

Your doctor may prescribe an antiviral medication like acyclovir and famciclovir. Other treatment options include emollients, which can reduce cracking and scabbing, numbing agents, and painkillers.

The lowdown

The herpes simplex virus is a lifelong infection once you have contracted it.²⁰ You might feel embarrassed about developing a cold sore, but you’re not alone. They are very common. The World Health Organization (WHO) reports that 3.7 billion people under the age of 50 have HSV-1 — that’s 67% of the global population.²¹

Triggers can facilitate an outbreak at any time. You can’t control all of these triggers, but keeping your stress levels down is a smart choice.

Have you considered clinical trials for Cold sores?

We make it easy for you to participate in a clinical trial for Cold sores, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

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