Key points at a glance
💉 Transmission via bodily fluids
In particular, blood, semen, pre-ejaculate, and vaginal and anal secretions, if they come into contact with mucous membranes or enter the bloodstream during sex.
🔬 A necessary condition for transmission
Transmission requires infectious fluid to come into contact with mucous membranes or enter the bloodstream directly.
⚠️ Highest risk during unprotected intercourse
The greatest risk of transmission arises from unprotected anal or vaginal sex, as well as from the sharing of injection equipment.
🛡️ Effective protective measures
Condoms, PrEP and effective HIV treatment resulting in an undetectable viral load significantly reduce the risk of transmission.
What does HIV transmission mean?
HIV transmission occurs when the virus passes from one infected person into another person’s body and establishes a permanent presence there. The exact moment of infection is referred to as HIV infection.
The colloquial terms ‘AIDS infection’ and ‘AIDS transmission’ are not technically correct: it is HIV that is transmitted, not AIDS. AIDS refers to an advanced stage of the disease that only occurs following an HIV infection that has gone untreated for a prolonged period. With treatment started in good time, this stage can now be prevented in the vast majority of cases.
Whether transmission occurs depends on contact with certain bodily fluids and mucous membranes, as well as on the protective measures taken.
How is HIV transmitted? Routes of transmission and risk
HIV can be transmitted primarily via these bodily fluids:
- Blood
- Sperm
- Vaginal and anal fluid
- Breast milk (breastfeeding)
For HIV infection to occur, infectious fluid must come into contact with mucous membranes or enter the bloodstream directly.
Typical situations involving a significant risk of HIV infection:
Very rare transmission from parent to child without medical care
Anal or vaginal sex without a condom with a person who is HIV-positive and not effectively treated
Shared injection use during drug consumption
HIV transmission: Where is there a real risk?
This table shows you at a glance in which situations HIV transmission is a realistic possibility and in which you don’t need to worry.
| Situation | HIV risk | Briefly explained |
|---|---|---|
| Anal intercourse | High risk without protection | HIV transmission is particularly likely during anal intercourse without a condom because semen or blood can come into direct contact with the sensitive intestinal mucosa. |
| Vaginal intercourse | Significant risk without protection | Vaginal intercourse can also lead to HIV infection through semen or blood on the mucous membrane if no condom, PrEP or effective therapy is used. |
| Oral sex | Mostly low risk | Oral sex poses a risk primarily when semen or blood enters the mouth and there are wounds or inflammation present. Oral sex without ejaculation in the mouth is considered low risk. |
| Sperm | High risk | HIV transmission through semen is one of the most common forms of transmission because seminal fluid can contain high amounts of the virus and easily comes into contact with mucous membranes during sex. |
| Pleasure drops | Lower, but not zero | Pre-ejaculate can also contain virus particles. The risk of HIV transmission via pre-ejaculate is significantly lower than via semen, but still exists during unprotected anal or vaginal sex. |
| Saliva | No risk | Saliva greatly dilutes the virus, so HIV transmission via saliva is considered impossible in everyday life as long as there is no clearly visible blood involved. |
| Kissing | No risk | HIV is not transmitted through kissing, even with the tongue. |
| Petting | No risk | Caressing, mutual masturbation and rubbing against each other without penetration rarely lead to HIV transmission, as long as there is no blood from fresh wounds. |
| Drug use with shared injection equipment | Very high risk | When sharing syringes, needles or other injection equipment, infectious blood can be transferred directly from one person to another, easily leading to HIV infection. |
Frequently asked questions
How is HIV transmitted?
HIV transmission mainly occurs via blood, semen, seminal fluid, vaginal and anal fluids if they come into contact with mucous membranes or directly into the blood. Typical situations are anal or vaginal intercourse without protection with a person who is HIV-positive and not effectively treated, as well as shared injection use when taking drugs.
Is there a risk of HIV during oral sex?
The risk of HIV during oral sex is usually low, but not completely eliminated. HIV through oral sex is particularly relevant if semen or blood enters the mouth and there are wounds or inflammations. Oral sex without ejaculation in the mouth is considered a low risk.
Can HIV be transmitted through kissing or saliva?
HIV cannot realistically be transmitted through kissing, including French kissing, in everyday life. Saliva dilutes the virus significantly; therefore, HIV transmission via saliva is considered virtually impossible, provided there is no clearly visible blood in the mouth.
What is the risk of transmission via semen?
Semen is one of the bodily fluids with the highest concentration of the virus and is therefore one of the main routes of HIV transmission. If semen comes into contact with the mucous membranes during unprotected anal or vaginal sex, the virus can enter the body through them. This risk can be significantly reduced by using condoms, PrEP or effective HIV treatment that results in an undetectable viral load.
