Kissing offers many health benefits, but may also transmit a small number of disease-causing bacteria and viruses. Bacteria and viruses in the saliva or blood of one person can be spread to another person by kissing. Some diseases are more easily spread than others.
How disease is spread
Diseases can be spread from person to person in a number of ways:
- Contact spread – some diseases are spread directly from person to person, for example during kissing, or indirectly when you touch a contaminated surface or object.
- Droplet spread – infected droplets from the nose and throat can usually travel around one metre before they drop onto a surface. Sometimes infected droplets can also linger in the air. Infection occurs when the infected droplet is inhaled or someone comes into contact with a contaminated surface or object.
- Airborne spread – some infected particles from the nose and throat can remain in the air for a long time because of their tiny size. They are called droplet nuclei and can be inhaled directly into the lungs.
Viruses that can be transmitted by kissing
Examples of illnesses caused by viruses that can be transmitted during kissing include:
- Colds – also known as upper respiratory tract infections. Many different viruses can cause the common cold. Colds are thought to be spread by direct contact with the virus. You could catch the cold from airborne droplets or by direct contact with secretions (fluids and mucous) from the infected person’s nose and throat.
- Glandular fever – also known as the kissing disease. Glandular fever is the common term for a viral infection called infectious mononucleosis, caused by the Epstein-Barr virus. The virus is spread through saliva and infection occurs through contact.
- Herpes infection – viruses that are considered part of the herpes family include Epstein-Barr, varicella-zoster (causes chickenpox) and herpes simplex (causes cold sores). Herpes simplex virus can be spread through direct contact with the virus when kissing. Herpes is most easily spread to others when the blisters are forming or have erupted. The virus can be ‘shed’ (spread to others) from the site of blisters even when they have healed. Chickenpox is easily spread from person to person by direct contact, droplets or airborne spread.
- Hepatitis B – kissing may also transmit this virus, although blood has higher levels of this virus than saliva. Infection can occur when infected blood and saliva come into direct contact with someone else’s bloodstream or mucous membranes. (Mucous membranes line various body cavities including the mouth and nose.) A person is more likely to be infected when kissing if they have open sores in or around the mouth.
- Warts – warts in the mouth can be spread through kissing, especially if there are areas of recent trauma.
Bacteria that can be transmitted by kissing
Examples of bacteria that can be transmitted during kissing include:
- Meningococcal disease – this is a potentially life-threatening condition which includes meningitis, inflammation of the membranes (meninges) that surround the brain and spinal cord, and septicaemia. These bacteria can be spread either through direct contact or via droplets. Studies show that, with respect to kissing, only deep kissing seems to be a risk factor.
- Tooth decay – the bacteria that cause tooth decay aren’t found in the mouths of newborn babies. A baby’s mouth must be colonised with infected saliva, which can be passed by a kiss on the lips.
Keep it in perspective
There is no need to give up kissing for the sake of your health and that of your loved ones. While disease-causing bugs can be transferred during a kiss, most won’t cause disease and the risk of serious disease is very small.
Prevention of infection while kissing
There are a number of things you can do to reduce the risk of passing on, or catching, an infection while kissing. You should try to:
- Avoid kissing when you or the other person is sick.
- Avoid kissing anyone on the lips when you, or they, have an active cold sore, warts or ulcers around the lips or in the mouth.
- Maintain good oral hygiene.
- Cough and sneeze into a hanky if you have a cold.
- See your doctor about immunisations. Vaccines are available to prevent some infectious diseases, such as chickenpox, hepatitis B and group C meningococcal infection.
Passionate kisses have health benefits
It’s not all doom and gloom. Research into passionate kissing has uncovered many valuable health benefits, including:
- Emotional bonding – kissing your partner is a fun, pleasurable and important part of physical intimacy and helps maintain a sense of togetherness and love.
- Stress reduction – kissing your partner, either tenderly or passionately, releases calming brain chemicals (neurotransmitters) that reduce stress levels and soothe the mind.
- Foreplay – deep kissing your partner can lead to sexual intercourse. Various studies show that sex enhances a person’s physical and mental health. For example, regular sex is protective against stress and depression.
- Metabolic boost – kissing burns kilojoules. The more passionate the kiss, the greater the metabolic boost.
- Healthier mouth – saliva contains substances that fight bacteria, viruses and fungi. Deep kissing increases the flow of saliva, which helps to keep the mouth, teeth and gums healthy.
- Increased immunity – exposure to germs that inhabit your partner’s mouth strengthens your immune system.
Where to get help
- Your doctor
- Your dentist
- Local council immunisation service
- Communicable Disease Control Unit, Department of Health Victoria Tel. 1300 651 160
- Immunisation Program, Department of Health Victoria Tel. 1300 882 008
- NURSE-ON-CALL Tel. 1300 606 024 – for expert health information and advice (24 hours, 7 days)
Things to remember
- Kissing can transmit many germs, including those that cause cold sores, glandular fever and tooth decay.
- Saliva can transmit various diseases, which means that kissing is a small but significant health risk.
- It’s not all doom and gloom. Research into passionate kissing has uncovered many valuable health benefits.
This page has been produced in consultation with and approved by:
Department of Health and Human Services - RHP&R - Health Protection - Communicable Disease Prevention and Control Unit
Page content currently being reviewed.
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