Evidence Based

Bladder Infection: Causes, Symptoms, Treatment

Written by Mathew Eng, PharmD | Reviewed by Ana Aleksic, MSc (Pharmacy) | Last updated:

SelfHacked has the strictest sourcing guidelines in the health industry and we almost exclusively link to medically peer-reviewed studies, usually on PubMed. We believe that the most accurate information is found directly in the scientific source.

We are dedicated to providing the most scientifically valid, unbiased, and comprehensive information on any given topic.

Our team comprises of trained MDs, PhDs, pharmacists, qualified scientists, and certified health and wellness specialists.

All of our content is written by scientists and people with a strong science background.

Our science team is put through the strictest vetting process in the health industry and we often reject applicants who have written articles for many of the largest health websites that are deemed trustworthy. Our science team must pass long technical science tests, difficult logical reasoning and reading comprehension tests. They are continually monitored by our internal peer-review process and if we see anyone making material science errors, we don't let them write for us again.

Our goal is to not have a single piece of inaccurate information on this website. If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please leave a comment or contact us at [email protected]

Note that each number in parentheses [1, 2, 3, etc.] is a clickable link to peer-reviewed scientific studies. A plus sign next to the number “[1+, 2+, etc...]” means that the information is found within the full scientific study rather than the abstract.

Bladder infection

A bladder infection is a common type of UTI, especially among women. This bacterial infection can be painful, stubborn, and distressing. The good news is that it is simple enough to treat in most cases, while certain lifestyle changes can help you prevent it from coming back. Learn how to spot the symptoms, what your doctor may prescribe, and which natural alternatives can help.

What Is a Bladder Infection?

The bladder’s role is to collect and store urine that has been filtered by the kidneys. An infection occurs when bacteria reach the bladder and infect it, which causes frequent and painful urination.

Bladder infections are the most common type of UTI (urinary tract infection), while UTIs are the most common type of bacterial infection in women [1].

Nearly half of all women will experience at least one UTI in their lifetime. UTIs can be stubborn and turn into a chronic problem. About 10% of women get an infection every year and almost half will have a second infection within a year [1+, 2+].

Women are four times more likely to get a UTIs than men. Bacteria from the stool can trigger an infection if they can reach the urethra–a tube that carries urine from the bladder to the place where it flushed from the body. Women have a shorter urethra, making it easier for bacteria to travel up to their bladder [2+].

Although UTIs are most common in younger women, they can occur at any age. This is especially a concern in children, the elderly, and in pregnant women, in whom infections can cause other health complications [2+].

A bladder infection is not sexually transmitted, although the two may some similar symptoms (like painful urination). Although sexual activity increases the risk of UTIs in women, the infection is not contagious. Women with UTIs won’t transfer the infection to their sexual partners [3].

The infection is typically treated with a short course of antibiotics, while various natural remedies and lifestyle changes can reduce your risk of it coming back.

Types of Infection

The first step in understanding bladder infections is differentiating them from other UTIs.

UTI (urinary tract infection) is an umbrella term for infections of the urinary tract. This includes the bladder, urethra, and kidneys.

Kidney infections are sometimes called an upper UTI. They are much more serious and require immediate medical care.

Bladder infections are known as lower UTIs.

This article mostly focuses on uncomplicated bladder infections. Uncomplicated UTIs are very common and occur in healthy, non-pregnant women.

On the other hand, a UTI is complicated when there is a risk of repeat infections or treatment failure. Complicated UTIs usually require longer antibiotic therapies and possibly other precautions. They involve [4]:

  • Men
  • Pregnant women
  • People with urinary tract abnormalities
  • Those with a suppressed immune system
  • Highly-resistant bacteria
  • People who use medical devices, including catheters and tubes
  • People with kidney transplants or kidney disease


Bladder infections can be caused by a variety of bacteria, but the most common type is E. coli, responsible for 90% of UTIs. E. coli is normally found in the gut [5].

Bladder infections usually start when fecal bacteria enter the urethra. From there, the bacteria move up the urinary tract until they reach the bladder and cause an infection. Women are more vulnerable because they have a shorter urethra, which reduces the distance the bacteria need to travel. If untreated, bacteria can continue up and cause a kidney infection [6].

Bacteria that cause bladder infections have cell structures that help them attach to the lining of the urinary system. This allows them to stick to the wall of the bladder and prevents the urine from washing them away. Some treatments work by blocking this attaching ability of bacteria [6].


Bladder infections don’t always cause symptoms. However, if you’re a woman experiencing painful and frequent urination, there’s a 90% chance that you have a UTI. You should see your doctor  [7+].

Symptoms of a bladder infection include [7+]:

  • Pain, discomfort, or burning when urinating
  • Frequent or urgent urination
  • Lower abdominal and pelvic pain
  • Cloudy or bloody urine

Some women have no signs or symptoms, and such infections are usually not treated or tested for. Studies show there are no negative long-term effects if you’re symptom-free [8, 7+].

Complicated Infections

Complicated bladder infections and kidney infections can cause additional symptoms. If the bacteria continue to spread, the prostate and blood may also become infected.

Symptoms of a complicated bladder or kidney infection include [7+]:

  • Fever
  • Chills
  • Mental confusion
  • Back or side pain
  • Nausea and vomiting

Risk Factors

Many factors may increase your risk of developing a bladder infection. Female anatomy is the main one and some risk factors are specific to women. For example, studies consistently show that sexual activity is the strongest risk factor in women. Using spermicides as birth control and a family history of UTIs are two others. Together, they can nearly double the risk of infection [3, 9].

Overall, the risk factors for bladder infections include [10]:

  • Sexual activity (in women)
  • New sex partner (in women)
  • Use of spermicide birth control (in women)
  • Mother with history of UTIs (in women)
  • Low estrogen (in postmenopausal women)
  • Age of first UTI at 15 years or younger
  • Conditions that reduce urine flow
  • Urinary or fecal incontinence
  • Urinary tract blockages
  • Diabetes
  • Being overweight
  • Suppressed immune system
  • Catheter use

Good intimate hygiene may reduce the risk of UTIs in young women and in pregnant women. However, research also shows that many practices commonly believed to prevent chronic, recurrent bladder infections may have no effect at all [11, 12, 3].

Factors that are NOT linked to recurrent bladder infections in women with frequent UTIs include [3]:

  • Urinating before or after sex
  • Wiping pattern
  • Hot tub use
  • Douching
  • Tampon use
  • Type of underwear/tights
  • Blood type


Simple bladder infections are often mild and respond quickly to antibiotics. However, certain populations will require special treatment and additional precautions.


Pregnant women have a higher risk of developing bladder and kidney infections. This is due to physical changes in the urinary tract caused by pregnancy [13].

All bladder infections are considered complicated in pregnancy, as the risk of serious complications is increased. Complications include high blood pressure in the mother, premature birth, and low birth weight [14, 15, 16].

Pregnant women have an increased risk of symptom-free bladder infections, which are often not a concern In non-pregnant women and go untreated. In pregnant women, these infections are more likely to progress to the kidneys. For this reason, it is important for pregnant women to test for infections even if they do not have symptoms [13].

Research shows that antibiotic treatment is important for preventing serious pregnancy complications in women with an infection. However, many commonly used antibiotics may cause defects in newborns. The usual first choices are safer penicillin-like antibiotics [13, 17].


Children can also get bladder infections, which is often harder to spot because the symptoms are not specific. Symptoms in children include fever, irritability, and vomiting [7+].

Serious bladder infections in children can lead to kidney scarring, which can reduce the kidneys’ ability to properly filter blood [18, 19, 20, 21].

Long-Term Risks

Recurrent bladder infections have been linked with an increased risk of bladder cancer in a study of almost 2k bladder cancer patients. A history of three or more bladder infections was also strongly associated with cancer. This does not mean that bladder infections will cause cancer, as many other underlying factors can increase the risk of both [22, 23].

What’s more, a review of 16 studies concluded that no such link exists in high-quality studies [24].

Conventional Treatment


Antibiotics are the mainstay treatment for bladder infections. Simple cases usually require a short course of antibiotics.

For a long time, the first choice was the combination drug trimethoprim/sulfamethoxazole, more commonly known by its brand names Bactrim or Septra.

According to the research, Bactrim is on par with other strong antibiotics. It also has fewer side effects. In clinical trials, the cure rate of Bactrim is about 80-100% [25, 26, 27, 28].

The main drawback of Bactrim is that bacterial resistance is steadily increasing. One study found that its cure rate dropped to 42% when treating resistant strains of bacteria. Many clinicians now recommend only using Bactrim in specific cases (when the local resistance rate is less than 20%) [29, 30, 31+].

Another commonly used antibiotic is nitrofurantoin — also called Macrobid or Macrodantin. Studies show that nitrofurantoin has a similar cure rate to Bactrim, averaging about 90%. The benefit of nitrofurantoin is that bacterial resistance is still low [28, 32, 31].

On the downside, it may have negative effects on the kidneys. Nitrofurantoin must be used cautiously in those with kidney disease and in the elderly [33].

Other antibiotics can be used for severe infections or highly-resistant bacteria. Stronger antibiotics come with more side effects and can be more expensive. Other factors that affect antibiotic choice include drug availability, allergies, and drug interactions [34, 31+]

Pain Medications

Pain-relief medications are sometimes used to reduce symptoms of pain and burning when urinating. However, painkillers only temporarily ease the discomfort and do not treat the underlying infection.

A popular pain-relief medication is phenazopyridine, which is available over-the-counter. Common brand names include Azo, Uristat, and Pyridium. This drug is able to concentrate in the urine to provide localized pain relief [35].

Phenazopyridine has been used in bladder infections for nearly a century, but research on its use is limited. One large study found that it improved symptoms in 61% of about 1.5k women [36].

Other painkillers, like NSAIDs and opioids, are sometimes used. According to research, opioids improve symptoms in 65.5% of women and their short-term use causes fewer side effects than Pyridium. However, opioids are strong painkillers that should be reserved for severe pain. Tolerance to them grows quickly and the risk of abuse is high [36].

Non-prescription NSAIDs are also a popular choice, as they reduce both pain and inflammation. Multiple studies have even explored the idea of using ibuprofen without antibiotics. They found that about 50%-66% of women were able to recover while only taking ibuprofen. However, these women also experienced more serious infection complications [37, 38].

Natural Alternatives

Various natural remedies can help prevent UTIs, reduce their recurrence, or slightly ease mild symptoms.


Many believe that cranberries are a safe and effective way to prevent UTIs. Despite numerous studies, the scientific community has not reached a clear verdict.

Cell-based studies confirm that cranberries contain compounds that prevent bacteria from attaching to the bladder [39].

In clinical trials, cranberries reduced the recurrence of bladder infections. One clinical trial of 150 women found that cranberries reduced the risk of infection by 20% [40, 41, 42].

However, not all research supports their effectiveness. A comprehensive review of 24 studies and over 4k people concluded that strong evidence to recommend their use is lacking [43].

Recommendations are further complicated by the fact that different strengths and forms of cranberry supplements are used. Cranberries can be taken as a juice, powder, or in pill form. It is unclear whether one form is more beneficial than another [44].

Ultimately, cranberries remain a popular natural alternative due to their low cost and minimal side effects [44, 42].

Vitamin C

Based on limited research, vitamin C may help prevent bladder infections.

Cell-based studies show that vitamin C makes the urine more acidic, turning it into a less hospitable environment for the bacteria [45, 46].

In one observational study of 468 women, vitamin C was weakly linked to lower infection risk. According to a different study, pregnant women who took daily vitamin C had fewer bladder infections [47+, 48].

You usually don’t need to take supplements to get enough vitamin C. Its content in food can vary, but eating vitamin C-dense foods will usually supply you with a decent amount of this vitamin. These include camu camu, citruses, acerola cherries, wild strawberries, and rose hips. Alternatively, vitamin C supplements will provide you with a therapeutic dose.


D-mannose is a type of sugar that naturally occurs in the human body. Its chemical structure is very similar to glucose.

Similar to cranberries, cell studies show that D-mannose prevents bacteria from sticking to the walls of the bladder. Theoretically, this allows for bacteria to be flushed out when urinating [49, 50].

Research on D-mannose is limited. One clinical trial of 308 people suggests that it is just as effective as nitrofurantoin, an antibiotic, and has significantly fewer side effects [51].

D-mannose is available as a nutritional supplement, in powder or capsule form.


Probiotics have become a popular and safe natural alternative for preventing infections. Research uncovered that probiotics can help with various types of infections. However, their benefit for bladder infections specifically is somewhat unclear.

A review of 9 studies concluded that there was not enough scientific evidence to say probiotics have a benefit–the difference between probiotics and placebo in reducing recurrent infections was minimal [52].

However, one particular probiotic does show promise. L. crispatus is a beneficial bacteria species that is commonly found in the vagina. A specific probiotic strain called CTV-05 is available as suppository capsules for vaginal use.

In one clinical trial, 100 women with recurrent bladder infections were given antibiotics plus L. crispatus or placebo. About 15% of women who took L. crispatus had an infection compared to 27% of placebo users. A safety study confirmed that this strain is safe and has minimal side effects [53, 54].


Compounds in garlic can fight bacteria, fungus, and viruses. Specifically, the compound called allicin seems to be responsible for the health benefits. Allicin is also anti-inflammatory properties, which may help reduce symptoms like pain and discomfort [55, 56, 57, 58].

Garlic may have a potential benefit for bladder infections. In two young women who failed multiple antibiotics, garlic reduced the frequency of infections and the severity of symptoms [59].

However, these women also received other natural remedies aside from garlic, including cranberries, probiotics, parsley, magnesium, evening primrose oil, and L-arginine. Because so many supplements were used, it is difficult to determine exactly what had the most beneficial effect [59].


L-Arginine is an amino acid that is used by the body to create proteins. L-arginine is typically found in foods such as red meat, fish, chicken, and dairy products.

L-arginine may play a role in fighting infections. One cell study shows that it activates cells in the immune system to attack bacteria. In an animal study, it improved circulation and metabolism in pigs with severe blood infections [60, 61].

The only evidence for L-arginine use in bladder infections comes from case reports. These used a combination of natural remedies (mentioned above), making it hard to judge the effectiveness of l-arginine alone [59].


Curiously, studies have examined the potential effectiveness of acupuncture in bladder infections.

Two small clinical trials were performed in Norway. The first study lasted for 6 months and included 67 women with a history of recurrent bladder infections. Of the women that received acupuncture, 85% were infection-free by the end, compared to only 36% of women who didn’t undergo it [62].

A second study included 98 women and also lasted 6 months. This time, 73% of women who received acupuncture did not have a bladder infection by the end of the study period. Of the other women, 52% were infection free [63].

This initial research supports the use of acupuncture for bladder infections. Larger clinical trials are needed to confirm these findings. Acupuncture is generally very safe when performed by a qualified practitioner, and may also help reduce pain and balance your stress response.

Uva Ursi (Bearberry)

Uva ursi is a species of plant that has been traditionally used to remedy bladder infections.

A compound called arbutin is the main active component. There is some concern that arbutin metabolizes into compounds that are toxic to the liver, but initial cell and animal studies propose that uva ursi is generally safe [64, 65].

Clinical research on uva ursi is limited. One clinical trial of 382 women found that uva ursi does not have an effect on the frequency of bladder infections or the severity of symptoms. Other larger trials are in progress [66].


Berberine is a plant compound used in traditional Chinese medicine. Several plants contain berberine including barberry, Indian barberry (“chutro”), and goldenseal.

One cell study shows that berberine prevents bacteria from attaching to the urinary tract surface, which would help detach bacteria in bladder infections. However, no clinical trials have been performed and its efficacy is unknown. Berberine supplements are safe and only rarely cause mild side effects [67].


Lifestyle Changes

Often, the first step in preventing bladder infections is changing certain behaviors, especially if you struggle with recurrent infections.

Despite the mainstream consensus, studies show that some popular methods of prevention may have no effect in women with recurrent infections. Behaviors like post-sex urination, wiping patterns, and tampon use are not strongly linked to recurrent infection risk  [68, 44].

Some experts recommend urinating after sex and wiping front to back. More broadly, good intimate hygiene maintains vaginal flora balance and supports reproductive health. Although they may not have a direct effect on recurrent bladder infections, using soaps and douches can change the vaginal pH and increase the risk of vaginal infections [68, 44, 69].

Sexual Activity & Birth Control Methods

Research shows that sexual activity is the strongest risk factor for bladder infections. You can still develop an infection if you’re not sexually active, though [70+, 44].

The use of spermicides as birth control is also strongly linked to infection. Intrauterine devices (IUDs) may also increase the risk and can lead to more complicated infections. Women with recurrent bladder infections should consider using a different form of birth control [70+, 44, 71].

Drink Plenty of Water

Successfully preventing bladder infections may be as simple as drinking enough water. Increasing water intake may help flush out bacteria and maintain an optimal urine acidity level [72+].

Observational studies show that low water intake and urine output are linked to bladder infections. One small study of 17 women found that women who tracked their hydration and water intake experienced fewer bladder infections [73, 74, 75].

No clinical trials have tested the effect of hydration on bladder infections. There is also no consensus on the optimal amount of water to drink. Despite this, adequate hydration remains a popular recommendation due to the many benefits and very few drawbacks of drinking enough water [76].


If you struggle with recurrent, severe bladder infections or UTIs, your doctor may prescribe certain medications to reduce the risk of the infection coming back and causing serious complications.


Women who experience frequent bladder infections may be prescribed antibiotics as a preventive measure. The same antibiotics are usually prescribed both for prevention and treatment, but the strategies can differ.

One strategy is to take antibiotics every day to prevent bladder infection. A large review of 19 studies found that continuous antibiotic use for 6-12 months reduces recurrent infection. However, daily antibiotics also increase the risk of side effects and antibiotic resistance [77].

Alternatively, antibiotics can be taken on a weekly or monthly basis. One study of 361 women found that weekly antibiotics were more effective than monthly doses [78].

Another approach is to take a single dose of antibiotics after sex. Several studies show that a post-sex dose of an antibiotic reduces bladder infections [79, 80, 81].

According to long-term research, antibiotics after sex are just as effective as taking daily antibiotics. This strategy reduces the quantity of antibiotics taken compared to daily use, which lowers side effects and bacterial resistance [77, 79, 80, 81].

The last strategy is to start antibiotic therapy at the first sign of infection. For this self-start method, women are taught how to self-diagnose and treat their bladder infection. Multiple clinical trials show this approach is effective and safe. According to one study, about 90% of women were able to accurately self-diagnose a bladder infection [82, 83, 84, 85].

However, self-start therapy is not as effective as daily antibiotics. One small study found that women who self-treated had 2.2 infections per year, compared to 0.2 infections per year with daily antibiotics [84].


Methenamine, also called Hiprex or Urex, is sometimes used to prevent bladder infections. Methenamine metabolizes to formaldehyde in the urine, which acts as an antibacterial. This drug is more effective when the urine is acidic. Increasing urine acidity by taking vitamin C or limiting milk products can be beneficial [86+].

In one large review of 13 studies and 2k people, methenamine prevented the majority of bladder infections. However, it did not work for people with abnormalities of the urinary tract. The rate of side effects was low, based on limited data [87].


Estrogen is an important hormone for maintaining vaginal health. It promotes the growth of good bacteria, which in turn block the overgrowth of harmful bacteria. Postmenopausal women produce less estrogen, which increases their risk of bladder infections [88].

A large review of 9 clinical trials including over 3k women reported that estrogen taken by mouth is not effective. Estrogen applied vaginally did reduce the frequency of infections. However, there was not enough evidence to support the use of one vaginal estrogen form over another (cream or vaginal ring) [89].


A vaccine that prevents bladder infection is an appealing prospect to some. However, the clinical effectiveness of newly developed vaccines is limited. In the U.S. there are currently no approved vaccines available for bladder infections [85].

The vaccine Uro-Vaxom (also called OM-89), is an oral vaccine available in Europe. It contains 18 different types of inactivated bacteria. An analysis of 10 clinical trials found that Uro-Vaxom reduces the frequency of infections more than any other vaccine. However, the quality of the studies was weak and the researchers could not make a definite recommendation [90].

A second vaccine called Solco-Urovac has also been developed in Europe. It comes as a suppository that is placed directly into the vagina. Research reviews show that Solco-Urovac also reduces the frequency of bladder infections. It requires a cycle of booster immunizations to be effective [90, 91].

Genetic Predispositions

Genetic differences may, in part, explain why some people are more susceptible to bladder infections.

One area of focus is on Toll-like receptors (TLRs). These are a group of proteins that help the immune system identify bacteria. Studies show that genetic variations that reduce TLRs cause an increase in recurrent bladder infections, as they reduce the body’s ability to recognize the invading bacteria and host an immune attack [92].

Certain variants in the following TLR genes were linked to bladder infections [93]:

Research also suggests that genetic variations of interleukin receptors may play a role. Interleukins are a large group of signaling proteins that play a variety of roles in the immune system. Certain genetic variations can interfere with interleukin binding, which may increase the risk of bladder infections.

Variants in the following interleukin receptor genes were linked to bladder infections [93]:

Limitations and Caveats

Limited Research

A great deal of research is available about bladder infections and strategies to treat or prevent them. Antibiotic treatment is one example. However, scientific evidence is lacking in some areas, especially for natural alternatives. More investigation is required before many of the natural products can be confidently recommended.

Different Types of Infection

The focus of the information presented here is on simple cases of bladder infections. Complicated bladder infections and kidney infections often require different treatments and precautions.


Bladder infections are among the most common bacterial infections in the world. They affect almost half of all women at one point in their life. For many, they are a recurring problem.

The most notable symptoms are urinating more often, accompanied by a burning sensation. Typical infections are usually simple enough to treat and don’t cause long-term complications. Bladder infections in pregnant women, men, or children can be more serious and require additional precautions.

Sexual activity, a family history of infection, and the use of spermicides are most strongly linked to bladder infections in women.

Treatment usually involves a short course of antibiotics, sometimes along with symptom-relieving painkillers.

You can make the following simple lifestyle changes to help with prevention or to reduce your risk of reinfection:

  • Stay hydrated and drink plenty of water
  • If you’re using spermicides or IUDs, consider switching to a different birth control method
  • Try acupuncture

Supplements that may help include:

  • Cranberries
  • Vitamin C
  • D-Mannose
  • Vaginal probiotics
  • Garlic
  • L-arginine
  • Bearberry
  • Berberine

About the Author

Mathew Eng

Mathew Eng

Mathew received his PharmD from the University of Hawaii and an undergraduate degree in Biology from the University of Washington.
Mathew is a licensed pharmacist with clinical experience in oncology, infectious disease, and diabetes management. He has a passion for personalized patient care and believes that education is essential to living a healthy life. His goal is to motivate individuals to find ways to manage their chronic conditions.

Click here to subscribe


1 Star2 Stars3 Stars4 Stars5 Stars
(1 votes, average: 5.00 out of 5)

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.