Understanding Long COVID, Epstein-Barr Virus (EBV) Reactivation and Why the Symptoms Overlap
Last Update: July 2026
Feeling as though you have glandular fever again after COVID is a common experience. Profound fatigue, sore throat, swollen lymph nodes and brain fog can occur as part of Long COVID itself, but researchers are also investigating whether COVID may allow Epstein-Barr virus (EBV), the virus that causes glandular fever, to reactivate in some people. At present, there is no single test that can distinguish the two, and many experts believe Long COVID and EBV reactivation may coexist in a subgroup of patients rather than being separate conditions.
Key Takeaways
- Long COVID can feel remarkably similar to glandular fever.
- Epstein-Barr virus (EBV) remains dormant for life after the initial infection.
- Research suggests EBV may reactivate in some people after COVID.
- Symptoms alone cannot reliably distinguish Long COVID from EBV reactivation.
- Blood tests may provide clues but must be interpreted carefully.
- Some people may have Long COVID with EBV reactivation rather than one or the other.
The fatigue. The sore throat that keeps returning. Mouth ulcers that seem to appear more often than they used to. Tender glands in your neck that never quite settle down. Even the heavy, flu-like feeling after doing too much. The symptoms seem strangely familiar, but you cannot immediately remember why. Then, almost out of nowhere, it comes back to you. Years ago, perhaps when you were fifteen or at university, you had glandular fever. You remember being exhausted for weeks after catching what many people called the “kissing disease”, and for a moment you wonder whether you are somehow living through it again.
It is a question thousands of people with Long COVID have asked themselves. Has my glandular fever come back? The answer is not as simple as yes or no. Long COVID itself can produce many of the same symptoms, including profound fatigue, brain fog, sore throat and swollen lymph nodes. At the same time, researchers are investigating whether COVID may allow Epstein-Barr virus (EBV), the virus that causes glandular fever, to reactivate in some people. That means the resemblance may not be a coincidence, but it also does not necessarily mean EBV is the whole explanation. In some people, both processes may be happening at the same time.
What Is Epstein-Barr Virus (EBV)?
Most people have already met Epstein-Barr virus, even if they have never heard its name. It is the virus that causes glandular fever, also known as infectious mononucleosis. Once you recover, the virus does not disappear. Instead, it quietly stays inside certain immune cells for the rest of your life.
Normally this is not a problem. Your immune system keeps EBV under such tight control that most people never think about it again. It is a bit like a campfire that has been completely covered with ash. The fire has not gone out, but there is not enough oxygen for it to burn.
COVID may temporarily change that balance. Fighting a new virus places enormous demands on the immune system, and researchers believe that in some people this reduces the normal “surveillance” that keeps dormant viruses under control. If the ash is disturbed, a few embers may begin glowing again. That does not mean the whole campfire is burning out of control, but it may help explain why some people experience symptoms that feel surprisingly similar to glandular fever months after COVID.
If you would like to understand this process in more detail, including why other dormant viruses such as herpes simplex and shingles can also reactivate, read our companion article “Viral Reactivation in Long COVID: Why EBV, Herpes and Shingles Can Return.”
Why They Feel So Similar
This is where the confusion starts.
If you compare the symptoms of Long COVID with the symptoms of glandular fever, they almost seem to blur into each other. Both can leave you exhausted after the smallest effort. Both can bring brain fog that makes simple conversations feel difficult. Both can cause a sore throat that never quite develops into a normal infection, swollen glands that come and go, aching muscles and the overwhelming feeling that your body is fighting something it cannot quite get on top of.
That is why so many people become convinced their Epstein-Barr virus must have reactivated. It feels logical. The symptoms match their memory so closely that it seems like the only explanation.
The problem is that Long COVID can produce many of these symptoms on its own. Looking at symptoms alone, even experienced clinicians often cannot say with confidence whether they are seeing Long COVID, EBV reactivation or both. The overlap is simply too great.
Could It Actually Be Both?
This is perhaps the biggest change in how researchers think about viral reactivation.
For a long time the question was framed as a choice. Either your symptoms were caused by Long COVID, or they were caused by Epstein-Barr virus becoming active again.
Researchers are increasingly questioning whether that is the wrong question altogether.
COVID can disrupt the immune system in several ways, including the cells responsible for keeping dormant viruses under control. At the same time, those same immune changes are thought to contribute directly to Long COVID itself. Instead of one condition replacing the other, it is entirely possible that the same immune disruption is driving both processes.
In other words, Long COVID may be the reason EBV has the opportunity to reactivate, while EBV reactivation may then add another layer of fatigue, sore throat or swollen lymph nodes. They are not necessarily competing explanations. For some people, they may simply be different chapters of the same story.
Why Blood Tests Often Create More Questions Than Answers
Many people hope that an EBV blood test will provide a simple answer.
Unfortunately, it rarely does.
Most adults have already been infected with EBV and will remain positive for EBV IgG antibodies for life. This tells you that your immune system has seen the virus before. It does not mean the virus has recently become active.
Other markers, including Early Antigen antibodies or EBV DNA testing in selected situations, may provide additional clues. However, no single blood test can prove that EBV reactivation is causing your Long COVID symptoms.
Doctors therefore have to interpret test results alongside your symptoms, medical history and the overall clinical picture rather than relying on one laboratory result.
So How Do Doctors Tell The Difference?
In truth, it is not always straightforward. Doctors can look for evidence that Epstein-Barr virus has become active again using blood tests and, in some situations, EBV DNA (PCR) testing. These investigations may provide useful clues, particularly when interpreted alongside your symptoms and medical history.
The difficulty is that even if tests suggest EBV reactivation, they cannot answer the bigger question: is EBV causing your symptoms, or is it simply another consequence of the immune changes triggered by Long COVID?
Some patterns may point more towards Long COVID, particularly if fatigue, brain fog, dizziness, post-exertional malaise and autonomic symptoms are the dominant features. Others, such as recurrent sore throat, swollen lymph nodes and compatible EBV test results, may raise suspicion that viral reactivation is also playing a role.
For some people, the most accurate answer may be that both processes are happening at the same time. Current research has not yet established whether EBV reactivation is driving Long COVID symptoms, contributing to them, or simply acting as a marker of underlying immune dysfunction.
Does EBV Reactivation Change Long COVID Treatment?
At the moment, not as much as many people hope.
If COVID has triggered reactivation of viruses such as herpes simplex (HSV) or shingles (varicella-zoster virus), effective antiviral treatments are already available and are routinely used. Epstein-Barr virus is different. Although antiviral medications can reduce viral replication in laboratory studies, clinical trials have not yet shown that they consistently improve symptoms in people with Long COVID or suspected EBV reactivation.
This is one reason researchers are still trying to understand what EBV reactivation actually represents. Is it directly contributing to Long COVID symptoms? Does it make an existing illness worse? Or is it simply a sign that the immune system has become dysregulated after COVID? At present, there is evidence supporting all three possibilities, but no definitive answer.
For now, treatment remains focused on managing the whole person rather than treating a single virus. Careful pacing, avoiding repeated post-exertional malaise (PEM), improving sleep, treating individual symptoms and addressing problems such as autonomic dysfunction remain the foundations of Long COVID care, regardless of whether EBV reactivation is also present.
As research continues, treatments may become more personalised. If future studies show that viral reactivation is driving symptoms in a subgroup of patients, targeted antiviral or immune-based therapies may become an important part of treatment. That is one of the key questions current Long COVID research is trying to answer.
The Real Question
eeling as though glandular fever has returned after COVID does not automatically mean Epstein-Barr virus has reactivated. Long COVID itself can produce many of the same symptoms, and for some people, EBV reactivation may be adding another layer to an already complex illness.
Researchers are increasingly moving away from asking whether it is Long COVID or EBV. Instead, they are trying to understand how the two might interact, why viral reactivation occurs in some people but not others, and whether it is driving symptoms, contributing to them, or simply reflecting an immune system that has not yet fully recovered.
Perhaps the real question is no longer:
“Has my glandular fever come back?”
It is:
“What has COVID changed in my immune system that makes my body feel this way?”
The answer is unlikely to be the same for everyone. Long COVID is increasingly understood as a condition involving several overlapping biological processes rather than a single cause. For some people, Epstein-Barr virus reactivation may be one piece of that puzzle. Understanding how those pieces fit together is what will ultimately lead to more accurate diagnoses, more personalised treatments, and better outcomes for people living with Long COVID.
Frequently asked questions about EBV reactivation
Why do old viruses reactivate after COVID?
Because SARS CoV 2 causes significant disruption to immune surveillance, particularly T cell function and natural killer cell activity, that normally keeps latent herpesviruses dormant. When that surveillance is compromised, viruses like EBV, HSV and VZV have more opportunity to reactivate. The immune disruption can persist long after the acute COVID infection resolves.
Why do I have shingles when I am under 50?
Shingles in younger adults is a recognised sign of immune disruption. VZV reactivation after COVID has been documented in people well below the usual risk age. If you have or suspect shingles, see a GP urgently as antivirals within 72 hours of rash onset significantly reduce both duration and the risk of lasting nerve pain.
Are cold sores and mouth ulcers the same thing?
Not always. Cold sores caused by HSV 1 begin as blisters at the lip border or inside the mouth. Aphthous ulcers, the more common non viral mouth ulcers, appear as painful white or grey erosions without the preceding blister phase. In Long COVID, both can be more frequent. HSV mouth ulcers tend to start as fluid filled blisters before breaking down; aphthous ulcers typically appear as erosions directly. Both can be triggered by immune stress.
What do swollen lymph nodes after COVID mean?
Lymph nodes enlarge when the immune system is actively processing an infection or reactivation. Tender, soft, mobile lymph nodes in the neck in the context of known or suspected EBV or HHV 6 reactivation are consistent with immune activation rather than something sinister. Hard, rapidly growing, non tender nodes or those accompanied by significant night sweats or weight loss warrant prompt clinical assessment.
Am I contagious during EBV reactivation?
In most everyday situations, no. EBV during reactivation produces much lower salivary viral levels than primary infection. Avoiding sharing drinks, cutlery or close saliva contact during symptomatic periods is a sufficient precaution. You are not a contagion risk to colleagues, children or most family members through normal interaction.
How do I read my EBV blood test results?
IgG positive means you have had EBV at some point. Almost all adults will be positive. IgM positive suggests recent or reactivated infection. EBV early antigen (EA D IgG) elevated is the most specific marker for reactivation and the one most relevant to Long COVID. Results need clinical context: ask your GP to interpret them alongside your symptoms rather than in isolation.
Do antivirals help with EBV reactivation in Long COVID?
For HSV and VZV, antivirals like valacyclovir demonstrably reduce outbreak severity and frequency. For EBV specifically in Long COVID, clinical trial evidence is limited. Most use is based on individual clinical judgment and some case series showing benefit. It is a legitimate conversation to have with your clinician, particularly if EBV reactivation markers are elevated alongside symptoms.
What about supplements like lysine and monolaurin?
Lysine has modest evidence for reducing cold sore frequency in some people. Monolaurin has laboratory antiviral properties but limited human trial evidence. Neither is dangerous at appropriate doses but neither has the evidence base of clinical antivirals. The biological rationale for lysine is more convincing than for most supplements in this space. Discuss with a clinician before starting.
Can viral reactivation trigger autoimmune problems?
Research suggests it can contribute. HHV 6 reactivation in Long COVID has been specifically associated with autoimmune reactions against myelin and tight junction proteins. EBV is a known trigger for autoimmune conditions including lupus and multiple sclerosis in susceptible individuals. Whether reactivation in Long COVID is triggering autoimmunity in some patients is an active research area.
Can I prevent viral reactivation if I have Long COVID?
There is currently no guaranteed way to prevent viral reactivation in Long COVID, but there are several steps that may help reduce the risk by supporting your immune system and avoiding known triggers.
One of the most important strategies is pacing. Overexertion can place additional stress on the immune system, and many people notice that cold sores, shingles or other viral symptoms appear after a significant physical or cognitive crash. Staying within your energy limits may help reduce these episodes.
Protecting your sleep is equally important. Poor-quality or insufficient sleep can impair immune function and increase susceptibility to viral reactivation. Managing stress, eating a balanced diet, treating nutritional deficiencies where present, and following your healthcare professional’s advice for underlying conditions may also support overall immune resilience.
If you experience frequent herpes simplex outbreaks or recurrent shingles, speak to your GP or specialist. Some people benefit from suppressive antiviral therapy, such as valaciclovir or aciclovir, although this is usually considered on an individual basis. At present, there is limited evidence that antiviral treatment prevents EBV reactivation in Long COVID, and research is ongoing
While no single strategy can eliminate the risk, maintaining the best possible overall health and avoiding repeated immune stress appears to be the most practical approach based on current evidence.
This article is for general information and education. It does not replace personalised medical advice. If you are experiencing frequent viral outbreaks, possible shingles, or swollen lymph nodes after COVID, please speak with your GP or a clinician familiar with Long COVID.
Sources and further reading
EBV and Long COVID EBV reactivation in 66.7% of Long COVID patients, original Pathogens study: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8233978/ EBV reactivation linked to fatigue and cognitive symptoms in Long COVID, Health Rising overview: https://www.healthrising.org/blog/2023/05/03/epstein-barr-virus-reactivation-fatigue-brainfog-long-covid/ EBV, gut brain axis and neurological symptoms in Long COVID, Molecular Psychiatry 2023: https://www.nature.com/articles/s41380-023-02161-5
HHV 6 and the wider herpesvirus picture HHV 6 reactivation, autoimmunity and Long COVID, Journal of Medical Virology 2024: https://onlinelibrary.wiley.com/doi/full/10.1002/jmv.29864 Persistent infection, EBV, HHV 6 and autoimmunity in Long COVID, PMC review: https://pmc.ncbi.nlm.nih.gov/articles/PMC9967513/ Viral suspects in Long COVID, ScienceDaily December 2025: https://www.sciencedaily.com/releases/2025/12/251214100911.htm
Bateman Horne Center on herpesvirus dysregulation: https://batemanhornecenter.org/herpes-virus-dysregulation-in-long-covid/ ENDOFFILE
About This EBV Reactivation and Long COVID Guide
This guide combines current research on viral reactivation with lived experience of Long COVID to explain how Epstein-Barr virus (EBV), herpes simplex virus (HSV), varicella zoster virus (shingles), HHV-6 and other latent viruses may become active after COVID-19. It aims to explain the evidence clearly without overstating what is known, recognising that viral reactivation is one possible contributor to Long COVID rather than a single explanation for everyone. As research continues to evolve, this article is reviewed and updated when important new findings become available. It is intended for educational purposes and should not replace personalised medical advice from your GP or healthcare professional.
More articles:
Long COVID and immune System
Exertional Malaise (PEM): What It Is and What Actually Helps
)How to Do a Sit and Stand Heart Rate Test at Home and What It Can Reveal
4 thoughts on “Why Do I Feel Like I Have Glandular Fever Again After COVID?”