A herpes outbreak typically starts with a warning sensation, most commonly tingling, itching, or burning at the spot where sores will eventually appear. This early phase, called the prodrome, can last up to 24 hours before any visible changes show up on the skin. Understanding what happens in your body during those early hours, and what to watch for in the days that follow, can help you recognize an outbreak sooner and respond faster.
What Happens Inside Your Body First
After your first herpes infection, the virus doesn’t leave your body. It retreats into clusters of nerve cells called ganglia, where it stays dormant. HSV-1 (the type most associated with oral herpes) typically lodges in the trigeminal ganglia near the base of the skull, while HSV-2 (more commonly linked to genital herpes) settles in the sacral ganglia at the base of the spine. The virus can remain quiet in these nerve cells for months or years.
When something triggers reactivation, the virus begins traveling along the nerve fiber toward the skin’s surface. It rides along tiny internal tracks called microtubules, hitching onto molecular motors that carry it from the nerve cell body outward to the skin. This journey is what produces those first sensations you feel before anything is visible. The virus is actively multiplying and moving toward the surface, irritating the nerve along the way.
The Prodrome: Your Earliest Warning
The prodrome is the window between when you first feel something and when sores actually appear. Most people describe it as tingling, itching, burning, or a vague ache in the area where previous outbreaks occurred. Some people feel referred pain in the lower back, buttocks, thighs, or knees, since the virus is traveling along nerves that branch into those areas.
This warning phase lasts up to 24 hours in most cases, though some people experience it for one to two days. Roughly 43 to 53 percent of people with recurrent outbreaks notice prodromal symptoms before sores develop. Not everyone gets a clear warning, but if you’ve had multiple outbreaks, you’ll likely start recognizing the pattern.
The prodrome is not just a feeling. The virus is already reaching the skin’s surface and replicating. You are contagious during this phase, even though nothing is visible yet. Skin-to-skin contact during the prodrome carries real transmission risk.
How Sores Develop Over Days
Within hours of the prodrome, the skin at the affected site may become red, warm, and slightly swollen. From there, the outbreak follows a predictable sequence.
- Blisters form. Small, fluid-filled blisters appear in clusters on a red base. They’re usually painful or tender. As the virus replicates and your immune system responds, the blisters grow and fill with fluid, dead immune cells, and cellular debris.
- Blisters rupture. The blisters eventually burst, sometimes on their own and sometimes from friction with clothing. They release clear or yellowish fluid and leave behind shallow red sores called ulcers. This is the most painful stage and also the most contagious.
- Ulcers crust and heal. The open sores gradually dry out, form a crust or scab, and heal. The full cycle from first symptom to healed skin typically takes one to two weeks for recurrent outbreaks, sometimes longer for a first episode.
First Outbreak vs. Repeat Outbreaks
A first herpes outbreak is almost always the most severe. It tends to produce more sores, larger blisters, and more pain than any recurrence. It also commonly comes with whole-body symptoms that feel like the flu: fever, headache, body aches, and swollen, tender lymph nodes in the groin. These systemic symptoms usually resolve within a week, but the sores themselves can take two to three weeks to fully heal.
Recurrent outbreaks start differently. They’re usually milder, more localized, and shorter. The flu-like symptoms rarely return, though swollen lymph nodes sometimes do. People who’ve been through a few recurrences often develop a strong sense of when one is starting based on the prodromal sensations alone. Over time, outbreaks tend to become less frequent and less intense as the immune system builds a stronger response to the virus.
What Triggers Reactivation
The virus reactivates when something disrupts the balance that keeps it dormant. Common triggers include physical or emotional stress, illness, fatigue, and a weakened immune system. For women, hormonal shifts during the menstrual cycle can trigger outbreaks, which is why some people notice a pattern tied to their period.
Sun exposure (particularly for oral herpes), skin irritation or friction, and surgery or trauma to the affected area can also provoke reactivation. Not every trigger will cause an outbreak every time, and some reactivations are subclinical, meaning the virus reaches the skin and sheds without producing visible sores. This asymptomatic shedding is one reason herpes spreads so efficiently: people can transmit the virus without knowing they’re doing so.
Recognizing an Outbreak Early
The sooner you recognize that tingling or burning for what it is, the sooner you can act. Antiviral medication is most effective when started during the prodrome or within the first 24 hours of sores appearing. If you have a prescription for episodic treatment, that early window is when to use it.
Pay attention to location. Herpes tends to recur in the same spot or very close to it, because the virus travels back along the same nerve path each time. If you feel an unusual itch or burn in a place where you’ve had sores before, that’s a strong signal. The combination of a familiar location and a tingling or burning sensation, even without any visible change to the skin, is enough to consider an outbreak underway.