Untreated Lyme Disease Years Later: Late Lyme Explained

Quick answer

Untreated Lyme disease can spread and cause problems months or even years after a tick bite. CDC lists arthritis with joint swelling, nerve problems and heart rhythm problems among later signs. In Europe, a slow skin condition called acrodermatitis chronica atrophicans can appear years later. Late Lyme disease is still treated with antibiotics, and most people improve.

What the guidelines say

CDC lists later signs of Lyme disease, which can appear days to months after a tick bite, including severe headaches and neck stiffness, more rashes, facial palsy, arthritis with severe joint pain and swelling, heart palpitations or an irregular heartbeat, inflammation of the brain and spinal cord, and nerve pain or numbness. CDC says Lyme arthritis can cause permanent joint damage without prompt treatment, and that varying degrees of permanent nerve damage may develop in people who go untreated and progress to late-stage disease.

What “late Lyme disease” means

Lyme disease is often described in three stages: early localized, early disseminated (spreading) and late. The MSD Manual notes that the early and late stages are usually separated by a period without symptoms, which is one reason some people don’t connect a later problem to a tick bite.

Late Lyme disease is an active infection. That makes it different from post-treatment Lyme disease syndrome, which describes symptoms that remain after treatment. For a stage-by-stage overview, see stages of Lyme disease.

What untreated Lyme can do years later

Lyme arthritis

Arthritis is a common late sign. CDC describes obvious swelling in one or a few large joints, most often the knee, typically starting within one to a few months after infection. The MSD Manual says arthritis develops in about 60% of people with untreated Lyme disease, usually within several months but sometimes up to 2 years after onset. Swelling can come and go. See Lyme arthritis.

Nerve and brain problems

Most nerve problems from Lyme happen in the early spread stage, CDC says, but late-stage disease can leave lasting nerve damage if untreated. The MSD Manual describes late nerve problems that include polyneuropathy (numbness, tingling or pain in the hands and feet) and a subtle brain effect with mood, memory and sleep problems. See neurological Lyme disease.

Heart problems

Lyme carditis happens when bacteria affect the heart’s electrical system, causing heart block. CDC says it occurs in about 1 in 100 Lyme cases reported to CDC. CDC lists heart palpitations or an irregular heartbeat among signs that can appear days to months after a bite, and says people with Lyme carditis generally recover within 1 to 6 weeks with treatment. See Lyme carditis.

Acrodermatitis chronica atrophicans (Europe)

This skin condition is a late sign seen mainly in people infected in Europe and is rare in the United States. It is caused mostly by the European species Borrelia afzelii. It mostly affects women aged 40 to 70, and it can appear months to years after the tick bite. The skin of the arms or legs first turns bluish-red and swollen, then slowly becomes very thin. If you have lived or traveled in Europe, tell your provider. See travel and Lyme disease.

When to get help

Get medical care promptly for a swollen joint, facial droop, severe headache with a stiff neck, or numbness or shooting pains, especially if you live in or have visited an area where Lyme disease is common. Call 911 for fainting, chest pain or severe shortness of breath.

Can late Lyme disease be treated?

Yes. Late Lyme disease is treated with antibiotics. Your provider will choose the medicine and length based on what is affected. Durations from the 2020 IDSA/AAN/ACR guideline and CDC include:

Problem	Typical treatment length
Lyme arthritis	28 days of oral antibiotics. If there is little or no response, the guideline suggests 2 to 4 weeks of IV ceftriaxone. If swelling continues after both, referral to a rheumatologist is suggested.
Nerve involvement (meningitis, nerve root or cranial nerve problems)	14 to 21 days, by mouth or IV depending on the problem
Brain or spinal cord involvement	IV antibiotics are recommended over oral
Lyme carditis	14 to 21 days in total
Acrodermatitis chronica atrophicans	21 to 28 days of oral antibiotics

How well does it work? The MSD Manual says antibiotics relieve late Lyme arthritis in most people and that late nerve abnormalities usually resolve completely. For the skin condition, outcomes are best when it is treated in the early, inflamed stage; skin thinning may only partly reverse. Some joint swelling can continue after two antibiotic courses. CDC says the cause of this is thought to be immune-related and that more antibiotics have not been shown to help, so a rheumatologist may suggest other treatments.

Two approaches at a glance

Late or long-term Lyme: how the guidelines approach it

	IDSA / AAN / ACR2020 guideline (followed by CDC)	ILADS2014 guideline
Lyme arthritis	28 days of oral antibiotics first; 2 to 4 weeks IV if little or no response; rheumatology if it continues	Not covered: the 2014 guideline addresses only tick-bite prevention, the rash and persistent symptoms
Ongoing symptoms after treatment, without objective signs	Recommends against more antibiotics	Recommends retreatment when chronic infection is judged a possible cause and quality of life is impaired

The IDSA/AAN/ACR 2020 guideline is the mainstream U.S. guideline (CDC says its treatment regimens are consistent with it) and grades its evidence. The ILADS 2014 guideline is used by some clinicians and relies more on clinical judgment. Sources: IDSA, ILADS.

Beat Lyme does not endorse either approach. Talk with your own clinician. How the two guidelines differ.

Lyme disease 20 years later

Could a tick bite from decades ago explain how you feel today? A Lyme problem can be found late, but many other conditions cause similar symptoms. CDC notes that Lyme disease is especially unlikely to be the cause if a recommended test is negative or if you have never lived in or traveled to an area where Lyme is common.

Patient-reported data from LymeDisease.org’s MyLymeData registry (2025 study) found that only 10% of people with chronic Lyme symptoms were diagnosed in the first month, which helps explain why some people are diagnosed years after they got sick. A good next step is a visit with a provider who will take a full history and order the right tests. See Lyme disease testing and preparing for your doctor visit.

What patients tell us

We are collecting real experiences about being diagnosed with Lyme years after a tick bite from people who have lived it, shared with their permission. As stories come in, they will appear here, clearly marked as personal experience rather than medical advice.

Share your experience

For the bigger picture on long-lasting symptoms, see chronic Lyme disease and long-term Lyme. This page is part of step 5 of How to beat Lyme.

Frequently asked questions

What happens if Lyme disease goes untreated for years?

The infection can spread and cause late problems such as arthritis with joint swelling, nerve problems and, mainly in Europe, a skin condition called acrodermatitis chronica atrophicans. CDC says untreated late disease can cause lasting joint or nerve damage.

Can late Lyme disease be cured with antibiotics?

Late Lyme is treated with antibiotics, usually for 2 to 4 weeks depending on what is affected. The MSD Manual says antibiotics relieve arthritis in most people and late nerve problems usually resolve completely. Some joint swelling can persist and may need a rheumatologist.

Can you have Lyme disease for 20 years and not know it?

Late problems can appear months to years after infection, and early and late stages are often separated by a symptom-free period. But many other conditions cause similar symptoms, so a careful evaluation is important.