Is amoxicillin good for a UTI?

If you’ve ever felt the painful symptoms of a urinary tract infection (UTI), it’s likely you want relief fast. You’re not alone—UTIs are common. They occur when bacteria like Escherichia coli (E. coli) infect the urinary tract organs, including the urethra (urethritis), bladder (cystitis), ureters, and kidneys (pyelonephritis).

Most urinary tract infections are caused by bacteria and are treated with antibiotics. Because of that, it’s easy to assume that amoxicillin—a wide-spectrum antibiotic that primary care providers commonly prescribe for certain infections—may be one of the first recommended treatment options for UTI. But it’s not always the case.

What medication a primary care provider will prescribe for a person with a UTI, depends on factors like the part of the urinary tract affected, whether it is a recurrent UTI, the bacteria suspected, the age of the patient, if the patient is pregnant, and the geographical area’s drug resistance rate.

Can amoxicillin treat a UTI? 

“Amoxicillin isn’t often a first-line treatment for urinary tract infections (UTIs),” says Jason Kovac, MD, Ph.D., a reproductive urologist and regional medical director for Posterity Health in Indiana, Ohio, and Michigan.

Amoxicillin is a beta-lactam antibiotic, which means it’s in the same class as penicillin. “It helps fight bacterial infections by disrupting the formation of bacterial cell walls,” says Max Ruvinov, Pharm.D., a clinical pharmacist at Mercy Health Care in Chesterfield, Missouri.

Amoxicillin is effective for treating certain types of UTI, especially those related to kidney and bladder infections. However, first-line treatments for UTIs typically are antibiotics Bactrim (trimethoprim-sulfamethoxazole) and Macrobid (nitrofurantoin). These antibiotics are more effective, have higher urinary concentrations, and have less impact on the normal gut bacterial flora. 

One older study indicates that amoxicillin, especially when combined with clavulanic acid, may act against bacteria like E. coli and Klebsiella, which commonly cause UTIs. Another older study suggests that taking amoxicillin with clavulanic acid reduces antibiotic resistance by blocking the medication from being destroyed by a bacterial enzyme called beta-lactamase. This means that the combination medication Augmentin (amoxicillin-clavulanic acid) is useful in the treatment of urinary tract infections caused by bacteria that are resistant to the beta-lactam class of drugs.

Is amoxicillin good for treating UTIs?

Although amoxicillin can treat some UTIs, it’s not always “the best” choice. Amoxicillin works on some strains of bacteria that cause urinary tract infections, but there is a high prevalence of resistance associated with this drug, which is why it may not be the ideal antibiotic for treating certain cases of UTI. The rates of microbial resistance to amoxicillin vary from region to region, with a rate of up to 40% in the United States.

While healthcare professionals don’t always recommend amoxicillin as the first line of treatment for UTI, there are cases where it can be prescribed instead of other antibiotics, e.g., when patients are allergic or sensitive to those other antibiotics or when they are taking medications that would interact with other antibiotics.

“One of the primary reasons amoxicillin may be prescribed is for the treatment of kidney infections due to its effectiveness against the bacteria responsible for the infections,” says Dr. Kovac. He adds that doctors may also prescribe amoxicillin as a means of “early intervention” when a UTI is suspected but a urine culture has not resulted. Depending on the urine culture results, the antibiotic may switch from amoxicillin to a narrow-spectrum antibiotic,  better targeting the microorganism causing the UTI.

There is no “one size fits it all” antibiotic treatment for urinary tract infections. No scientific evidence shows that one particular antibiotic is the best for all UTI cases. The ideal medicine will depend on the type of UTI, whether it’s a recurring infection, if there is any co-existing health condition (like pre-existing kidney failure or pregnancy), and the overall health status of an individual.

Amoxicillin dosage for UTI

For UTI treatment, adults are typically prescribed 250 to 500 mg of amoxicillin every eight hours, according to Dr. Ruvinov, while children are prescribed a dosage based on their body weight, commonly 20 to 40 mg/kg/day, divided into three doses. 

Dr. Kovac adds that amoxicillin treatment typically lasts for two to three days–however, the duration will vary. Some people may need to take antibiotics for three to five days, while others may require a seven-day treatment course or more. When on the proper medication and in the absence of complications, response to treatment is often evident within 24 to 48 hours

Side effects of amoxicillin for UTI

“While amoxicillin is generally safe, it can sometimes cause side effects,” Dr. Ruvinov says, pointing out common side effects like nausea and diarrhea. Rarely, it can cause more severe side effects, like:

• Bruising or changes in skin color
• Serious allergic reaction, which may cause skin rashes
• Joint or muscle pain
• Severe diarrhea that contains blood
• Dark-colored pee and pale poop
  

To minimize the risk of side effects, here are some things you can do:

• Ensure you are taking your medications as written on the prescription bottle. 
• Limit alcohol consumption when on amoxicillin, as alcohol can contribute to dehydration, worsen symptoms like nausea, and be detrimental when you are dealing with an infection.
• Speak to your provider or pharmacist before taking any other medication while on amoxicillin.
• Discuss any unusual symptoms or signs of allergic reaction during or after the treatment duration.
• Drink a lot of water or eat more fluid-based foods like soup to hydrate the body and potentially reduce the risk of recurrent UTIs.
  

“Patients should discuss their complete medical history and current medication regimen with their healthcare provider to prevent potential drug interactions and complications associated with amoxicillin,” Dr. Ruvinov advises.

Can UTI symptoms linger after taking antibiotics?

Prescription antibiotics often offer quick relief from UTI symptoms within a few days of starting treatment. However, in some cases, symptoms may persist even after completing a course of antibiotics. “This could be attributed to various reasons; for example, conditions like interstitial cystitis or kidney stones may present with similar symptoms,” Dr. Kovac explains. 

There are also cases where UTI symptoms may worsen after taking antibiotics. Dr. Kovac says this may be due to a number of reasons, such as:

• Disruption of the natural bacterial balance (which is beneficial to health), fostering the overgrowth of antibiotic-resistant bacterial strains
• Ineffective targeting of specific bacteria, leading to persistent or recurrent infection
• Adverse side effects like diarrhea or allergic reactions, intensifying overall symptoms

It is important that individuals speak with their healthcare provider when they experience unusual symptoms, even if they are associated with common conditions like a UTI. Symptoms to look out for to suspect a UTI include:

• Frequent urination
• Pain or a burning sensation when urinating
• Lower back pain
• Nausea and vomiting
• Blood in urine
• Frequent urge to urinate even when the bladder is empty
• Cramping in the lower abdominal area
  

Amoxicillin and most other antibiotics are not available over the counter in the United States. People who experience UTI symptoms should consider getting an examination and seeking medical advice regarding treatment. You should also speak to your healthcare provider about any medication side effects and follow up if your symptoms persist or worsen after treatment.