Muscle Weakness and Constipation—But Tests Are Normal?
Quick Answer: Muscle weakness and constipation in Lyme disease may be caused by neurologic and autonomic nervous system dysfunction—even when imaging and gastrointestinal tests are normal.
This is a classic Lyme disease pattern: real symptoms—but normal tests.
Why this matters: When muscle weakness and constipation occur together, they may point to a single underlying cause—Lyme disease affecting both the nervous system and gut.
For a broader view of how these patterns fit together, see Lyme disease symptoms.
When Tests Are Normal but Symptoms Persist
An 80-year-old man, later diagnosed with Lyme disease, was admitted with left leg paresis (muscle weakness), along with pain and sensory disturbances in his abdomen.
He also had a rash, severe abdominal pain, and constipation that had been ongoing for 4 to 5 weeks.
The patient had visited three medical centers. However, a colonoscopy and CT scan of the abdomen did not explain the severity of his symptoms.
This “normal test but real symptoms” pattern is common in Lyme disease.
To understand this pattern, it helps to look at how Lyme disease affects both nerve function and gut regulation.
Muscle Weakness and Constipation in Lyme Disease
This pattern often overlaps with abdominal pain in Lyme disease and constipation, where symptoms reflect autonomic dysfunction rather than a primary gastrointestinal disorder.
Lyme disease can affect:
- Peripheral nerves → causing weakness or paresis
- Autonomic nervous system → disrupting gut motility
These systems can be affected together—explaining why symptoms may seem unrelated at first.
Clues That Point to Lyme Disease
The rash appeared as a “patchy, pruritic redness with pustules,” particularly on the flank and abdomen, the authors state.
Testing revealed Borrelia-specific IgM and IgG antibodies, consistent with neuroborreliosis.
The authors concluded:
“The disease initially manifested with autonomic symptoms (constipation) and severe abdominal pain, followed by neurologic involvement.”
This progression—from gut symptoms to neurologic symptoms—is a key diagnostic clue.
Why Constipation Occurs in Lyme Disease
“The patient’s constipation is likely due to autonomic involvement,” the authors note.
The autonomic nervous system controls involuntary functions such as digestion.
When affected by Lyme disease, it may lead to:
- Slowed intestinal movement
- Constipation
- Abdominal discomfort
This can occur even when gastrointestinal testing appears normal.
Response to Treatment
The patient’s symptoms resolved completely following a 21-day course of doxycycline.
After treatment:
- Muscle weakness resolved
- Constipation improved
- Abdominal pain disappeared
He was able to resume his prior level of activity within two months.
This outcome highlights that symptoms caused by Lyme-related nerve dysfunction may be reversible.
Why This Pattern Is Often Missed
Lyme disease may be overlooked when:
- Symptoms span multiple systems
- Tests for gastrointestinal disease are normal
- Neurologic and digestive symptoms are treated separately
See more on Lyme disease misdiagnosis.
This can delay diagnosis and prolong symptoms.
Clinical Takeaway
Recognizing this pattern—muscle weakness plus constipation with normal testing—can help avoid missed Lyme diagnoses and lead to effective treatment.
Related Articles:
Abdominal pain, ileus and constipation due to Lyme disease
Lyme disease triggers neuropathy in the legs
Atypical symptoms of Lyme disease
References:
- Ahrend H et al. Atypical Acute Neuroborreliosis With Leg Paresis and Constipation. In Vivo. 2024.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
Dr. Cameron, you may want to suggest to Lyme patients with muscle weakness that they begin taking the supplement Urolithin A. It is an anti aging “post biotic” or stomach metabolite. There are studies that back up it’s efficacy, in this exact space.
I have had Lyme since 2011. One of my biggest complaints over the years has been leg muscle weakness. Have you had that also?
I had Lyme disease in July of 2022. I was treated with doxycycline for 14 days.i had extreme pain in both legs when I was first infected. But now ,almost 2 years later I legs still ache. Not as bad as when I was diagnosed. I also have insomnia since the Lyme disease diagnosis. Trying to find a Dr who believes me is impoi.
You are not alone
Yes, we are alone. Because no one knows how to treat and diagnose advanced Lyme w/o the drugs almost killing us. . I was initially treated by Dr.Burrascano who helped me the first time and we know why he had to stop practicing. Criminal and have lost all hope.
So many people don’t believe when you have symptoms. To them, Lyme Disease has an easy fix with a pill for 14 days.
Back in Spring of 2016, I suddenly was battling flu-like symptoms, but so much worse. The arthritis pain in my hands so severe I could only close them part way, both of my legs hurt to the point that I was crying, headaches, every muscle was on fire effecting nerves felt like I never knew was humanly possible. I had several unexplained patches of a red rash. After a week of suffering, I finally was driven to my doctor. At that single visit, blood was drawn to check for Lyme. It came back positive. Put on doxy pills for 2 weeks. Within that time, 3 bullseye circles had shown up on my inner thighs. Never knew I was infected.
I spent months trying to walk on both weak legs, my arms lost strength, and my brain fog had taken over. I had even gone to an Infectious Disease Doctor in Pittsburgh/Monroeville. He told me nothing more could be done. It was like getting slapped with a death sentence.
I was 52 yrs old back then, healthy and strong and enjoyed gardening. Now I can only shop holding onto a cart or walking short distances. Gardening is no Ionger possible. I am technically disabled and depressed. My grandkids keep me going.
So sorry about the long reply, but this was the first I had ever told strangers of my battle with the disease.
It can be crippling as I found out.
Thanks for sharing. There are too many with similar stories.
I had Lyme disease as a young teen and developed strange neurological symptoms over the next two decades, such as a drop foot and upper motor neuron signs. I have no idea if Lyme was the cause, and neurologists don’t know either. I haven’t seen a lot of research on the incidence of Lyme and upper motor neuron symptoms.
I have not seen much either.