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Antibiotics for UTI when pregnant
Health,  Women's health

Antibiotics for UTI when pregnant: recommendations

Urinary-tract infection (UTI) is a common condition experienced in pregnancy. Physiological changes to the urinary tract during the pregnancy, such as dilation of the urethra and decreased bladder capacity, increase the risk of urinary infections or thrush like problems. (Hebak, 2019). UTI is an umbrella term which defines infection of the bladder (cystitis), kidneys, or urethra. In this post, I am looking at recommended antibiotics in UTI when a pregnant patient is affected by this condition. 

UTI common symptoms

Common symptoms of UTI may include:
  • Difficulties/discomfort when urinating
  • Increased frequency of urination
  • Lower abdominal pain (lower stomach)
  • A strong smell of urine
  • Cloudy looking urine or urine which contains a blood
  • Feeling unwell
In contrast, asymptomatic bacteriuria, which is also possible in the pregnancy, is defined as the presence of the bacteria in the urine with no symptoms or signs of urinary tract infection.

UTI in pregnancy: test for bacteria

It is recommended to test for bacteria before treatment with antibiotics for UTI in pregnancy is commenced. Tets for bacteria presence is usually performed by obtaining a midstream urine sample. Certain patients may be offered an antibiotic, for example, a pregnant patient who was previously treated with an antibiotic, which may have led to the growth of resistant bacteria or pregnant patients with previous test results.

Recommended antibiotics for UTI when pregnant

The choice of antibiotic is usually reviewed once results from the microbiological test are available. Based on the test results, the antibiotic for UTI when pregnant may also be changed to select the best antibiotic according to specific bacteria, which is causing the infection.

Antibiotics for UTI when pregnant: first choice treatment

1. Nitrofurantoin
Nitrofurantoin is recommended as the first-line antibiotic for UTI when pregnant. Nitrofurantoin is usually prescribed in the form of modified-release capsules (each capsule contains 100mg of nitrofurantoin), taken twice a day for 7 days. Nitrofurantoin can be prescribed if other forms, for example, tablets, usually at a different dose (the frequency and number of tablets taken). Check for the prescriber’s instructions on the recommended dose and the duration of the treatment.   Product information for nitrofurantoin confirms the long-term usage of this antibiotic since 1952 and its suitability as a treatment choice in pregnancy as well documented (eMC, 2020). Nitrofurantoin should be avoided at term in the pregnancy, during labour and delivery of the baby.
Nitrofurantoin for UTI in pregnancy: common side effects
Nitrofurantoin is generally well tolerated; however, as with many other drugs, there is a possibility of side effects. Possible side effects associated with nitrofurantoin treatment (frequency not known):
  • Upset stomach (abdominal pain, diarrhoea, nausea)
  • Yellow or brown discolouration of urine (this is not harmful)

Antibiotics for UTI when pregnant: second choice treatment

Second choice antibiotics for UTI in pregnancy are used when no improvement in UTI symptoms is achieved after 48 hours of treatment or when the initial choice is not suitable, for example, due to urine culture test results.
1. Cefalexin
Cefalexin is usually taken at the dose of 500mg twice daily for 7 days. Follow your prescriber’s instructions on the dosage and treatment. Cefalexin comes in the form of capsules, tablets, and oral suspension. Cefalexin can be used in pregnancy, and it is not known to be harmful (NICE, 2020).
Cefalexin: common side effects
Common side effects associated with cefalexin use may include:
  • Gastrointestinal side effects: diarrhoea, nausea (feeling sick)
 2. Amoxicillin
Amoxicillin is recommended as a second-line treatment for UTI when pregnant only if bacterial test results confirm that this antibiotic is an effective treatment. Amoxicillin is usually taken three times a day for 7 days. Follow the directions of your GP for dosage instructions and the duration of the treatment.   Amoxicillin comes in the form of capsules and oral suspensions.
Amoxicillin: common side effects
Common side effects which can be experienced by patients taking amoxicillin may include:
  • Gastro-intestinal side effects: diarrhoea, nausea (feeling sick)

Other advice for management of UTI when pregnant

Pregnant patients with UTI should maintain a good intake of fluids to avoid dehydration. Pregnant women should seek urgent medical review if symptoms get worse at any time or when the condition fails to improve 48 hours of starting antibiotics (NICE, 2019).

Treatment of asymptomatic bacteriuria when pregnant

Asymptomatic bacteriuria (ASB) is a common condition during pregnancy. As the name suggests, this condition is characterised by the presence of bacteria in the urine without the symptoms of lower UTI (cystitis) or upper tract infection. It is estimated that asymptomatic bacteriuria affects between 2-10% of pregnancies (Glaser & Schaeffer, 2015). When left untreated, ASB can lead to the development of acute pyelonephritis in pregnancy (sudden kidney infection), which can cause preterm birth and low birth weight (Smaill & Vazquez, 2015). Routine screening for ASB early in pregnancy is recommended. All pregnant women should be screened for asymptomatic bacteriuria during their 1st antenatal appointment. A sample of urine is sent to check for the presence of bacterial infection.

What is the treatment recommendation for asymptomatic bacteriuria in pregnancy?

The recommendation for treatment of ABS in pregnancy follows the same choice of antibiotic selection as the management of UTI discussed in earlier paragraphs. Main antibiotics used include:
  • Nitrofurantoin
  • Amoxicillin (when urine test confirms suitability)
  • Cefalexin

Antibiotics not allowed for UTI when pregnant

Trimethoprim used to be a first-line treatment in the management of UTIs in non-pregnant women. Pregnant women should not take trimethoprim.

Pain relief associated with UTI in pregnancy

Pregnant patients have minimal choice when it comes to the management of pain. NICE guidelines recommend simple analgesia such as paracetamol for pain relief of UTI in pregnancy (NICE, 2019).           The use of a hot water bottle may help with the management of pain. Placing a hot water bottle on the stomach, back, or between thighs, may elevate the pain.

OTC products for UTI in pregnancy

Over the counter products for containing sodium or potassium citrate are available to relieve symptoms of cystitis, a common form of UTI. Over the counter products reduce the acidity of the urine, which helps to reduce pain and burning sensation when urinating, a common symptom of cystitis and UTI. Popular over the counter products include CanesOasis (sodium citrate) and Cystopurin (potassium citrate). Both products are not recommended for the management of UTI symptoms in pregnancy. Advice is to see a doctor before any of the products are used when pregnant. References eMC (2020). SmPC: Macrobid Capsules 100mg B.P Available at: Accessed on 10/03/2020 Glaser AP , Schaeffer AJ . Urinary tract infection and bacteriuria in pregnancy. Urol Clin North Am 2015;42:547–60.doi:10.1016/j.ucl.2015.05.004 Available at: Accessed on 11/03/2020 Hebak Patricia (2019). Urinary Tract Infection In Pregnancy. Available at: Accessed on 11/03/2020 NICE (2019). Urinary tract infection (lower) – women. Available at:!scenario:3 Accessed on 10/03/2020 NICE (2020). Cefalexin. Available at: Accessed on 10/03/2020 Smaill FM, Vazquez JC. Antibiotics for asymptomatic bacteriuria in pregnancy. Cochrane Database Syst Rev. 2015;(8):CD000490. Published 2015 Aug 7. doi:10.1002/14651858.CD000490.pub3 Available at: Accessed on 11/03/2020

I am a community pharmacist working in UK. I blog about drugs, health and pharmacy.

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