Cat scratch fever, known medically as cat scratch disease, typically starts with a small bump at the site of a cat scratch or bite, followed by swollen lymph nodes that develop one to seven weeks later. Most cases resolve on their own within a few weeks, but the infection follows a recognizable pattern that’s helpful to know, especially since the early skin bump is easy to overlook.
The First Sign: A Bump at the Scratch Site
About 3 to 10 days after a cat scratches or bites you, a small raised bump (a papule or pustule) appears at the wound site. It can look like a pimple, a small blister, or a cluster of reddish nodules near the original scratch. This bump is easy to dismiss as a normal part of healing, but it’s actually the first sign that the bacteria has entered your skin. The lesion typically sticks around for a few weeks before fading on its own.
Not every cat scratch causes this. The infection comes from a specific bacterium carried in cat saliva and on their claws, and kittens are more likely to transmit it than adult cats. You can also get it if a cat licks an open wound or scratch on your skin.
Swollen Lymph Nodes: The Hallmark Symptom
The most recognizable symptom of cat scratch fever is swollen, tender lymph nodes. These usually appear one to seven weeks after the initial bump and are the reason most people end up at a doctor’s office. The swelling happens in whichever lymph nodes are closest to the scratch site, so the location gives a clue about where the infection entered.
In about 46 percent of cases, the swelling shows up in the armpit or elbow area, which makes sense given that most scratches happen on the hands and arms. Around 26 percent of people develop swollen nodes in the neck or jaw, 18 percent in the groin (from scratches on the legs or feet), and the remaining 10 percent in less common spots like near the ears, collarbone, or chest.
The affected nodes can swell to a noticeable size and feel warm and tender to the touch. In some cases they become large enough to be visible. This swelling lasts two to eight weeks in most people, though it can occasionally persist for several months. The nodes sometimes fill with pus and need to be drained, but that’s not the norm.
Flu-Like Symptoms
Beyond the bump and the swollen nodes, many people with cat scratch fever experience a general sense of feeling unwell. Common symptoms include low-grade fever, fatigue, headache, decreased appetite, and joint pain. These tend to come on around the same time as the lymph node swelling and can last for days to a couple of weeks. Not everyone gets these systemic symptoms, but when they show up alongside swollen nodes and a recent cat scratch, the combination is a strong signal.
Eye Involvement
In a small percentage of cases, the infection enters through the eye, usually when someone pets an infected cat and then rubs their eye. This leads to a condition called Parinaud oculoglandular syndrome, which causes redness and irritation in one eye, eye pain, excessive tearing, and small bumps on the inner surface of the eyelid. The lymph nodes near the affected ear also swell. It looks and feels quite different from pink eye, partly because it’s almost always limited to one eye and comes with that distinctive node swelling nearby.
Rare Neurological Complications
Serious complications from cat scratch fever are uncommon, but they do happen. Neurological involvement occurs in roughly 2 percent of cases, and when it does, encephalopathy (swelling and dysfunction of the brain) accounts for about 90 percent of those cases. Symptoms can include seizures, confusion, altered consciousness, and generalized weakness. In published case series, seizures occurred in 46 to 80 percent of patients who developed this brain involvement.
Other rare neurological effects include problems with specific nerves controlling eye movement or facial expression, inflammation of the optic nerve, involuntary movements, and difficulty with balance and coordination. One case report described sudden weakness on one side of the body and difficulty speaking in a 7-year-old girl. These complications are serious but tend to resolve, and the vast majority of cat scratch fever cases never come close to this territory.
Higher Risk for Immunocompromised People
People with weakened immune systems, including those with advanced HIV, organ transplant recipients, and people undergoing chemotherapy, can develop a more aggressive form of the infection. Instead of simple swollen nodes, they may develop a condition called bacillary angiomatosis: raised, purple to bright red, berry-like skin lesions that bleed heavily if bumped or cut. These can resemble other serious skin conditions, making diagnosis tricky.
In immunocompromised patients, the infection can also spread to internal organs, particularly the liver, but also the lungs, brain, bones, and spleen. This is a fundamentally different disease course from what healthy people experience, and it requires treatment rather than watchful waiting.
What Recovery Looks Like
For most people, and especially children, cat scratch fever resolves without antibiotics. The bump fades, the lymph nodes gradually shrink back to normal over two to eight weeks, and the flu-like symptoms pass. The timeline from first scratch to full recovery is typically a few months from start to finish, with the worst of it concentrated in those weeks of active lymph node swelling.
If a cat scratch or bite turns red and swollen and you start developing fever, headache, fatigue, joint pain, or loss of appetite, those symptoms together are worth getting evaluated. The combination of a known cat exposure, a bump at the wound site, and regional lymph node swelling is usually enough for a clear clinical picture.