Azithromycin is the preferred antibiotic for treating Campylobacter infections. Most people with campylobacteriosis recover without antibiotics at all, but when treatment is needed, a short course of azithromycin, typically 500 mg daily for three days, clears the infection effectively.
Most Cases Don’t Need Antibiotics
Campylobacter gastroenteritis is usually self-limiting, meaning your immune system handles it on its own. Symptoms like watery diarrhea, cramping, and nausea typically resolve within a week. Antibiotics are not a mainstay of treatment in otherwise healthy people. When they are used, they shorten symptoms by about 1.3 days on average, which matters most when the illness is severe enough to disrupt your life.
Antibiotics become important when the infection is more aggressive or the person is more vulnerable. The key situations where treatment is recommended include:
- Bloody diarrhea (dysentery)
- High fever alongside diarrhea
- Severe abdominal pain or frequent watery stools that are worsening
- Weakened immune system from conditions like HIV, chemotherapy, or organ transplant medications
- Older adults who are at higher risk of complications
If your symptoms are mild and improving after a few days, your body is likely clearing the infection without help.
Azithromycin: The First Choice
Azithromycin works by blocking the bacteria’s ability to build proteins, which stops them from growing and reproducing. It’s effective against both major disease-causing species, Campylobacter jejuni and Campylobacter coli, and resistance to it remains relatively low compared to other antibiotics.
For adults, there are three common dosing options. The simplest is a single 1,000 mg dose taken all at once, though nausea can be a problem with that much at one time. Splitting that same 1,000 mg into two doses on the same day reduces the nausea. The third option is 500 mg once a day for three days, which tends to be the most tolerable. All three regimens are considered equally effective.
For children, the standard dose is 10 mg per kilogram of body weight per day for three days. So a 20 kg (44 lb) child would receive 200 mg daily.
Other Antibiotics That Work
Erythromycin is the main alternative to azithromycin and belongs to the same drug class. It has been used against Campylobacter for decades. The adult dose is 250 mg four times a day for five days, and the pediatric dose is 40 mg per kilogram per day split into four doses over five days. It’s effective but less convenient because of the more frequent dosing and longer course. Some people also experience more stomach upset with erythromycin than with azithromycin.
Fluoroquinolones like ciprofloxacin were once the go-to treatment for bacterial diarrhea, including Campylobacter. That has changed dramatically. Resistance to ciprofloxacin has surged over the past decade. One study comparing Campylobacter isolates from 2010-2011 to 2023-2024 found that ciprofloxacin resistance in C. jejuni jumped by about 38%, and in C. coli by about 42%. Ciprofloxacin and tetracycline are now the two antibiotics Campylobacter strains most commonly resist. Because of this, fluoroquinolones are no longer recommended as first-line treatment, especially for infections acquired in South or Southeast Asia where resistance rates are highest.
Tetracyclines face similar resistance problems and carry additional restrictions. They should be avoided during pregnancy and in young children because they can affect bone and tooth development.
Why Resistance Patterns Matter for You
If you picked up Campylobacter while traveling, where you traveled affects which antibiotic is most likely to work. Fluoroquinolone-resistant Campylobacter is especially common in parts of Asia, but rising resistance has been documented globally. This is a major reason azithromycin has become the default choice. It remains reliably effective in most regions, and the CDC lists it as the preferred treatment for severe or dysenteric travelers’ diarrhea.
When your stool sample is sent for testing, the lab can determine exactly which antibiotics the specific strain responds to. Newer PCR-based tests detect Campylobacter with about 97% sensitivity, far better than traditional stool cultures, which catch only about 37% of cases. However, PCR tests identify the bacteria’s DNA rather than growing live organisms, so they can’t test for antibiotic susceptibility the way a culture can. If your initial test is PCR-based and your symptoms aren’t improving on azithromycin, a follow-up culture may be needed.
Hydration Is the Foundation
Regardless of whether you take antibiotics, replacing lost fluids is the most important part of treatment. Campylobacter diarrhea can cause significant dehydration, particularly in children and older adults. Water alone isn’t ideal because it doesn’t replace the electrolytes you’re losing. Oral rehydration solutions, available over the counter, are designed with specific ratios of sodium, potassium, and glucose that help your intestines absorb fluid efficiently. The WHO formula contains about 90 mmol/L of sodium, 20 mmol/L of potassium, and a small amount of glucose.
For mild dehydration (feeling thirsty, slightly dry mouth, reduced urine), sipping an oral rehydration solution steadily over several hours is usually enough. For moderate dehydration (dizziness, very dark urine, no tears when crying in children), more aggressive rehydration with the same approach is recommended. If you or your child can’t keep fluids down at all, that’s a sign medical attention is needed.
What Recovery Looks Like
With or without antibiotics, most people start feeling better within two to five days. The diarrhea usually resolves first, followed by cramping and fatigue. Antibiotics are most effective when started early in the illness, ideally within the first few days of symptoms. Starting them later still helps in severe cases but has less impact on shortening the overall course.
One thing to watch for: symptoms that seem to resolve and then return, or joint pain developing a week or two after the diarrhea clears. A small percentage of Campylobacter infections trigger reactive arthritis, an inflammatory response in the joints that isn’t caused by the bacteria directly spreading but by the immune system’s overreaction. This is uncommon but worth knowing about, since it requires different treatment than the original infection.