What is the tick bite timeline, stage by stage?
Early Lyme disease, the illness a tick bite can cause, is usually described in three stages: early localized, early disseminated, and late disseminated. Disseminated means the infection has spread beyond the bite (Mayo Clinic). The CDC groups the same course into two parts for clinicians, early localized and disseminated, so only Mayo Clinic splits the later part in two (CDC).
Treat the windows as rough, because the stages can overlap and some people never have the typical early stage, which means a later sign can be the first thing anyone notices. The rough timeline looks like this.
- First hours to 2 days: the bite itself, which is usually painless and often fades on its own.
- 3 to 30 days: early localized disease, with a spreading rash or flu-like symptoms.
- About 3 to 10 weeks: early disseminated disease, with more rashes and nerve or heart signs.
- About 2 to 12 months: late disseminated disease, most often a swollen, painful knee or other large joint.
What do the early stages of a tick bite look like?
Most of the time it looks like very little. A tick bite usually doesn't hurt and you often won't feel it, so many people learn about it only when they spot the tick or a small red bump (MedlinePlus). A bump or patch of redness that appears right away and looks like a mosquito bite is common. It generally fades in 1 to 2 days and doesn't mean Lyme disease (CDC).
A spot that appears within the first 48 hours, is often itchy, and stays under about 5 cm (2 inches) across fits an allergic-type reaction to the bite, which can follow a bite from any kind of tick (CDC). Redness and discomfort at a lone star bite can come simply from that tick's saliva irritating skin (CDC).
A tick that is still on you changes from day to day. Left in place, it can stay attached for several days and swell to ten times its size or more as it fills with blood (NIH News in Health). So a speck that keeps growing over a day or two may be the tick itself, not a skin reaction. A bite that turns warmer, more swollen, or more painful, or starts to ooze pus, has a different problem, a possible infection of the skin (Nemours KidsHealth).
What is the early tick bite rash, and when does it show up?
The rash of early Lyme disease starts at the bite after a delay of 3 to 30 days, with about 7 days the average. It grows slowly over several days, up to 12 inches (30 cm) or more across. It may feel warm but is rarely itchy or painful, and as it grows the middle sometimes clears, which is how the bull's-eye look forms. It can appear on any part of the body (CDC).
People picture a clean ring, but that is the less common look. Only about one rash in five shows the classic bull's-eye (FDA). The CDC's clinician manual shows solid red patches, bluish ones, one with a crusted center, and a faint rash behind a knee (CDC). The no-bullseye guide goes further into rashes without a ring, and the bullseye rash page shows what a ring can look like.
Where the bite was decides whether you will see the rash at all. Ticks tend to attach in hard-to-see places such as the groin, armpits, and scalp (MedlinePlus), so a patch there can go unseen for days unless you use a mirror or ask someone to look.
If you do find a mark, photographing it each day or two in the same light shows how fast it's growing, and a clinician will want to know that. BiteSight can suggest a likely match for a bite from a photo, but it can't say which stage anyone is in.
Can early Lyme disease happen without a rash?
Yes, since only about 70 to 80 percent of infected people get the rash (CDC), and some people get many red spots instead of a ring (American Academy of Family Physicians). Fever, chills, headache, fatigue, muscle and joint aches, and swollen lymph nodes can all appear with no rash (CDC).
Many people never see the tick either. A young tick, called a nymph, is about the size of a poppy seed, and people with Lyme are often unaware of a bite before they get sick (CDC). Most people who get Lyme disease don't remember a bite, and many of its symptoms look like other conditions (Mayo Clinic). That is why a flu-like week a few weeks after time in tick country is worth mentioning to a clinician even when you remember no bite (NIH News in Health).
What is early disseminated Lyme disease, weeks later?
If early infection goes untreated, it can spread. The second stage often shows up within 3 to 10 weeks of the bite and is more widespread than the first (Mayo Clinic). The signs include new rashes on other parts of the body, a stiff or painful neck, weakness on one or both sides of the face, pain, numbness, or weakness in the hands or feet, and heartbeat changes. The skin sign is more than one rash, including ones in places the tick never touched (CDC).
A drooping face, on one side or both, is called facial palsy, and the CDC lists it with an irregular heartbeat, dizziness, and shortness of breath among the signs that come after the early ones (CDC). When the heart is involved, the manual calls it Lyme carditis, which can mean heart block or inflammation of the heart and in rare cases is fatal (CDC).
What is the late stage of a tick bite?
Late disseminated disease usually begins 2 to 12 months after the bite. In the United States it most often shows up as arthritis in large joints, particularly the knees, and the pain, swelling, or stiffness can last a long time or come and go (Mayo Clinic). If a knee swells months after a bite you may not even remember, tell the clinician about the time you spent in tick country.
Finding it early changes this stage. People treated in the early stages usually recover rapidly and completely, and early diagnosis with proper treatment can help prevent late disease (CDC). Which treatment fits you is a question for a clinician, not for a web page.
Do most tick bites go through these stages?
No, because tick bites usually cause no symptoms. Not every tick carries germs, and not every infected tick passes them on, so doctors don't need to treat most bites (Nemours KidsHealth).
Where you are matters. Across the country, the share of blacklegged ticks carrying Lyme bacteria runs from none to over 50 percent depending on the area and the tick's life stage, and in most of the southeastern states they're almost never infected. Lone star, American dog, Rocky Mountain wood, and brown dog ticks can't pass on Lyme bacteria, though they carry other illnesses (CDC).
Lone star ticks can also lead somewhere else entirely, to alpha-gal syndrome, a red meat allergy, so the stages above don't describe those bites (CDC). The alpha-gal guide covers that. Time attached counts as well. The CDC says a tick generally has to stay attached for more than 24 hours to pass on Lyme bacteria, and the FDA gives 36 to 48 hours or more, so the sources differ on the exact hours (CDC, FDA).
When should you call a clinician?
Call if a rash or fever shows up within several weeks of taking a tick off, and tell the clinician about the bite, when it happened, and where you most likely picked the tick up (CDC). The same goes if you never found a tick but live in, or recently traveled to, a place where Lyme disease is common and you have these signs (CDC).
Later signs call for a visit in the same way: a drooping face, a stiff neck with a severe headache, new rashes away from the bite, or a knee or other large joint that is swollen and painful (CDC). For a child, call if you don't know how long the tick was on, if any rash appears, or if symptoms start (Nemours KidsHealth).
Get care now for an irregular heartbeat, fainting, trouble breathing, swelling of the face or mouth, or a fever in a baby. Whether Lyme is behind any of those is a question for the clinician who sees you.
Want to keep a record of the mark?
A spot that shows up right away usually fades in a day or two, and a growing patch or a new fever is the reason to call. If you want a dated picture of the mark, or of a tick you still have, photograph it in the BiteSight iPhone app, or use the same photo tool on the web if you don't have an iPhone. There's no Android app yet.
