Herpes Simplex Virus (HSV-1 & HSV-2): Symptoms, Treatment, and Testing in Singapore
Herpes simplex virus (HSV) is one of the most common viral infections worldwide. There are two types: HSV-1, usually associated with cold sores around the mouth, and HSV-2, the most common cause of genital herpes. Both can affect the genital area, and both can spread even when no sores are visible.
Medically reviewed by Dr. Qiao Yufei, MD
This guide covers HSV-1 vs HSV-2, how the virus spreads, symptoms, asymptomatic shedding, antiviral treatment, and how testing works at Mediway Medical Centre. HSV is one of several conditions covered in our broader STDs in Singapore overview.
What is herpes simplex virus?
Herpes simplex virus (HSV) is a contagious viral infection that affects an estimated several billion people worldwide. According to the World Health Organization (WHO), around 3.7 billion people under age 50 have HSV-1 (oral or genital) and around 491 million people aged 15–49 have genital HSV-2. The virus is lifelong: after initial infection, HSV stays dormant in nerve cells and can periodically reactivate, with or without visible sores.
HSV-1 vs HSV-2: what's the difference?
Both types are part of the same herpes simplex virus family but cause different patterns of infection. Knowing which type you have can guide testing decisions and inform your partners.
Most often: oral herpes
- Cold sores or fever blisters around the lips and mouth
- Often acquired in childhood through non-sexual contact
- Can also cause genital herpes through oral sex
- Genital HSV-1 typically has fewer recurrences than genital HSV-2
Most often: genital herpes
- Genital sores, blisters, or ulcers, including anal herpes
- Spread through vaginal, anal, and genital-to-genital contact
- Strongly associated with sexually active adults
- Recurrent outbreaks are more common than with HSV-1
There is no cure for HSV today. The virus stays in the body for life, but it is highly manageable. Antiviral medication shortens outbreaks and reduces transmission risk to partners; daily suppressive therapy can keep many people outbreak-free for long periods.
How HSV spreads
HSV spreads through direct skin-to-skin or mucous-membrane contact with an infected person. Transmission can happen even when no sores are visible.
- Oral-to-oral: kissing, sharing eating utensils or lip balm (mainly HSV-1)
- Oral-to-genital: oral sex can transmit HSV-1 to the genitals, or HSV-2 to the mouth
- Genital-to-genital: vaginal, anal, and genital intercourse (mainly HSV-2; anal herpes is well-recognised)
- Mother to baby: a pregnant woman with active genital HSV can pass the virus during childbirth, causing neonatal herpes, which is rare but serious
You cannot get HSV from
- Toilet seats, swimming pools, hot tubs, or shared bathrooms
- Casual contact such as hugging or shaking hands
Asymptomatic shedding: why HSV is so common
One of the most important things to understand about HSV is asymptomatic viral shedding: the virus can be active on skin or mucous membranes without any visible sores or symptoms. This is the main reason most people who acquire HSV catch it from a partner who did not know they had it.
- People with HSV shed virus on roughly 10 to 20% of days, with or without symptoms (CDC)
- Daily antiviral suppressive therapy reduces (but does not eliminate) shedding
- Suppressive therapy plus condom use lowers transmission risk to a partner by around 50%
- Most people with HSV-2 are unaware they carry it; routine testing is the only way to know
Symptoms of HSV infection
Many people with HSV have no symptoms or only very mild symptoms. When symptoms do occur, the first outbreak is typically the most severe; recurrences tend to be milder and shorter, often signalled by tingling or itching before any sores appear.
Common symptoms
- Painful blisters or ulcers on the lips, mouth, genitals, or anus
- Tingling, itching, or burning before blisters appear (the "prodrome")
- Flu-like symptoms (fever, body aches, swollen lymph nodes), particularly in the first outbreak
- Pain or burning during urination if genital sores are present
- Red, cracked, or sore patches inside the mouth (oral HSV)
Triggers for recurrences
Common triggers include physical or emotional stress, illness, fatigue, hormonal changes (such as menstruation), strong sunlight (for cold sores), and a weakened immune system.
How herpes is diagnosed
Two main testing approaches at Mediway Medical Centre:
- Swab test (PCR): a sample is taken directly from an active sore and tested by polymerase chain reaction. This is the most accurate method when a sore is present, ideally within the first 48 hours of the sore appearing.
- Blood test (HSV-1 and HSV-2 IgG antibodies): detects past or current infection by measuring antibodies. Useful when no sore is visible, or to identify a chronic infection. False negatives can occur in early infection (it can take 4 to 12 weeks for antibodies to develop).
At-home herpes test kits are widely advertised, but their accuracy varies and a clinic-based test (especially PCR from an active sore) is more reliable. If you have a current outbreak or recent exposure, book a clinic visit.
Treatment: antiviral medications
HSV is treated with oral antiviral medications. They do not cure the infection, but they suppress viral activity, shorten outbreaks, and reduce the risk of transmission to partners.
Two treatment approaches
- Episodic therapy: antiviral started at the first sign of an outbreak (the prodrome) and taken for 5 to 10 days. Shortens outbreaks and reduces severity.
- Suppressive therapy: a low daily dose of antiviral taken continuously. Reduces outbreak frequency by 70 to 80% and lowers transmission risk to partners by around 50%. Useful for people with frequent recurrences or who are in a relationship with an HSV-negative partner.
Topical creams and lifestyle
Over-the-counter topical creams may relieve mild discomfort but are less effective than oral antivirals. A balanced diet, sleep, stress management, and a strong immune system can help reduce recurrence frequency.
How to reduce HSV transmission risk
Complete prevention is not possible because HSV can be transmitted from skin not covered by a condom, but several strategies meaningfully reduce risk:
- Condoms: consistent and correct use reduces HSV-2 transmission by around 30 to 50%
- Avoid sex during outbreaks: transmission risk is highest when sores are present or you feel a prodrome
- Suppressive antiviral therapy: in the infected partner, reduces transmission risk to partners by approximately 50% (per 2024 European Guidelines)
- Open communication: discuss HSV status with partners; both partners can then make informed choices
- Regular STI screening: especially if you have new or multiple partners
What happens if HSV is left untreated?
Most untreated HSV does not cause serious medical complications, but it can affect quality of life and increase certain risks:
- Recurrent outbreaks: frequent painful sores, particularly in the first 1 to 2 years after acquiring HSV
- Increased HIV risk: genital herpes increases the likelihood of acquiring or transmitting HIV
- Neonatal herpes: rare but serious infection in newborns if a mother has an active infection during childbirth
- Psychological impact: stigma, anxiety, or depression, especially around the time of diagnosis. Counselling and patient education make a meaningful difference.
Frequently asked questions
01 What is herpes?
Herpes is a common viral infection caused by the Herpes Simplex Virus (HSV). There are two main types: HSV-1 (commonly causes oral herpes / cold sores) and HSV-2 (commonly causes genital herpes). Once infected, the virus remains in the body for life and may cause periodic outbreaks. Many people have HSV without symptoms or with mild symptoms they do not recognise. Herpes is not curable but can be managed with antiviral medication.
02 What is the difference between HSV-1 and HSV-2?
HSV-1 most commonly causes oral herpes (cold sores) but can also cause genital herpes through oral sex. HSV-2 most commonly causes genital herpes and is usually transmitted through sexual contact. Both viruses are lifelong once acquired, but symptoms can be managed with antiviral medication. A blood test can distinguish between them. HSV-2 typically causes more frequent genital outbreaks than HSV-1 in the same site.
03 What are the symptoms of herpes?
Many people have no symptoms or only mild symptoms they do not recognise. When symptoms occur, they may include painful blisters or sores at the site of infection (mouth, genitals, anus), tingling or itching before sores appear, fever, swollen glands, body aches, and pain when urinating (genital). The first outbreak is often the most severe. Subsequent outbreaks are usually milder and less frequent over time.
04 How long after exposure do herpes symptoms appear?
If symptoms appear after a first HSV infection, they often develop within 2 to 12 days after exposure, although timing can vary. Some people remain asymptomatic indefinitely or only notice symptoms much later. Because of this variability, blood testing (HSV IgG) can help confirm past or current infection even when no sores are present.
05 How do you get herpes?
Herpes is transmitted through direct skin-to-skin or mucous-membrane contact: oral-to-oral contact (such as kissing when cold sores or oral shedding are present), oral-to-genital contact (oral sex), or genital-to-genital contact (vaginal, anal, or genital intercourse for HSV-2). Mother-to-baby transmission can also occur during childbirth (neonatal herpes). HSV can be transmitted even when no sores are visible, due to asymptomatic viral shedding.
06 What is asymptomatic shedding?
Asymptomatic shedding occurs when the herpes virus is active on the skin or mucous membranes without causing visible sores or symptoms. The infected person feels normal but can still transmit the virus to a partner. Asymptomatic shedding is a major reason HSV spreads, and it is why many infected people do not know they have HSV. Suppressive antiviral therapy and consistent condom use can reduce shedding and transmission risk.
07 Is herpes curable?
No. Herpes is not curable. Once infected, HSV remains in the body for life. However, herpes is manageable with antiviral medication, which can shorten outbreaks, reduce their frequency, and lower transmission risk to partners. For many adults, HSV does not cause serious long-term health problems, but it can be more serious in newborns, in pregnant patients near delivery, and in people with weakened immune systems.
08 How is herpes treated?
Herpes is treated with prescription antiviral medications. Your doctor will choose the appropriate antiviral and dosing based on whether it is your first outbreak, recurrent outbreaks, or daily suppressive therapy. Two main approaches: episodic therapy (started at the first sign of an outbreak to shorten it) or suppressive therapy (daily antiviral to reduce outbreak frequency and transmission risk). Discuss the right approach with your doctor.
09 How can I prevent herpes?
Herpes risk can be reduced (not eliminated) by using condoms consistently during vaginal, anal, or oral sex, avoiding sexual contact during outbreaks, and considering daily suppressive antiviral therapy if your partner has known HSV. Open conversations with partners about HSV status support informed decisions. Avoid kissing or oral contact when you or a partner has visible cold sores.
10 Where can I get tested for herpes in Singapore?
You can get tested at Mediway through our STD testing service. HSV is typically diagnosed via swab from an active sore (most accurate when sores are present) or blood test (HSV IgG antibodies) to detect past or current infection. The doctor will recommend the appropriate test based on your symptoms and exposure history. Learn more on our STD testing in Singapore page, or speak to our team for a confidential consultation.
Related conditions and next steps
References: CDC: Genital herpes (detailed) · WHO: Herpes simplex virus · HealthHub Singapore: Herpes
This page is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Consult a qualified healthcare professional for diagnosis and treatment of suspected herpes infection.