During the first few weeks of being infected with human immunodeficiency virus (HIV), most people — roughly two-thirds — experience a mix of flu-like symptoms that indicate their body is reacting to the virus. After being exposed to the virus, your immune system jumps into action to get control of the infection and clear it from your body.
This early phase of infection, known as acute retroviral syndrome or acute HIV infection, can be so mild that certain individuals may not even notice they’re sick. People often mistake the symptoms, such as a fever or headache, for the flu, mononucleosis or tonsillitis.
In most cases, these early signs only last a week or two. “It basically feels like a flu reaction since the initial HIV viral load is very high,” said Dr. Monica Gandhi, an infectious disease specialist at the University of California, San Francisco.
Regardless of whether you feel sick, these first few weeks are some of the most infectious. Being aware of these symptoms, especially if you recently had sexual contact with a new partner or multiple partners, can help you get tested and take steps to reduce the impact HIV can have on your health ― in the short and long term.
Here’s what to look for if you think you might have been exposed to HIV:
Fever
The most common early warning sign is a fever, usually at 100.4ºF or higher. One report investigating acute HIV symptoms in 155 patients found that 66% reported a fever.
Soon after infection, the virus swims throughout your bloodstream and replicates. The viral load is very high after seroconversion (becoming infected with HIV), and a fever is the body’s way of trying to fight the virus, explains Gandhi.
“The usual response to a pathogen is to mount a fever in order to try to recruit immune cells to kill the pathogen,” Gandhi said.
Fatigue
Fatigue, or a general sense of weariness or exhaustion, is common in many infections, HIV included. The fatigue may be mild, but, in some cases, it can be so intense that it impacts quality of life, social connectedness, job productivity, level of physical activity, well-being and health-seeking behaviors, research shows.
“When one’s body is fighting infections, there’s a lot of chemicals that get released called cytokines,” said Dr. Philip Grant, an infectious diseases specialist at Stanford Medicine. While these chemicals help combat infections, that process can be exhausting, he added.
Headache
After seroconversion, your head may also start to ache. One study found that over half of HIV-positive participants who were seen at a clinic reported a headache. It’s the most common neurological complaint associated with HIV.
According to Grant, some people with acute HIV may develop meningitis or inflammation in the meninges caused by the virus entering cerebral-spinal fluid. That can cause a headache, according to Grant, but a headache can also just be the body’s typical response to all the cytokines swirling around.
Swollen Lymph Nodes
Your lymph nodes — located in the armpit, groin and neck areas — may also become enlarged. Part of the immune system is located in the lymph nodes, and in the early days of an infection, your body boosts the production of immune cells.
“That’s why you get more cells there and why the lymph nodes are getting swollen,” Grant said.
Many people notice the swollen glands in their neck, Grant said. He added that people usually won’t have a single swollen node but a cluster of swollen lymph nodes. While lymph nodes can swell up in other areas, like the groin and armpits, many people don’t notice them as readily as the ones in their neck.
Sore Throat
Another common early symptom of HIV is a sore throat or tonsillitis. According to Grant, tonsils in the back of your throat are lymphatic tissue, meaning it’s an area where the body is actively fighting infection. They help filter out germs and protect your body from harm, according to the Cleveland Clinic.
If your tonsils are inflamed, it may be uncomfortable, even painful, to swallow. Grant says he’s had patients go to the emergency room assuming they had tonsillitis or a strep infection only to learn they have HIV.
Rash
Some people will suddenly develop a rash, which will cause a patch of your skin to feel itchy, red and painful. A rash occurs in about 50% of people infected with HIV, usually three or so days after the fever appears.
HIV-related rashes can occur anywhere on the body, but they’re often located on the torso and face, evidence suggests. Again, the rash is a common symptom of many infections, including chicken pox, measles, and hand-foot-and-mouth disease, so it may not be initially obvious it’s related to HIV, Grant said.
Muscle And Joint Pain
Roughly half of people with an acute HIV infection experience muscle aches, according to the National Institutes of Health. They typically set in a week after contracting HIV and, again, feel similar to the aches triggered by influenza.
Cytokines promote inflammation throughout your body. “When cytokines are released, the body can feel very tired with muscle and joint aches, which makes the body ‘slow down’ as it tries to fight an infection,” Gandhi said.
The main takeaway: “It’s a lot like the flu, it’s almost indistinguishable,” Grant explained. If you have any of these early HIV symptoms and recently had sex with more than one partner or have had sex with someone whose sexual history you don’t know about (or your partner has), it’s important to check in with a healthier provider and get tested.
You can do so at your primary care doctor’s office, through your local health department, a health clinic, or at an HIV testing site (here’s a nationwide directory).
The sooner you get tested, the earlier you can start treatment, if need be. When given in the first few weeks of infection, antiretrovirals can inhibit viral replication, reduce symptoms, and, ultimately, improve long-term health outcomes. These early signs may not be obvious, but being aware of them and taking action as soon as possible can help you protect your health and avoid transmitting the infection to others.