Azithromycin is a macrolide antibiotic that is used to treat bacterial infections such as bronchitis, pneumonia, and other infections of the ear, nose, throat and reproductive organs.  One of the most common side effects of antibiotics, in general, is gastrointestinal (stomach) problems.  The most common side effects listed in the drug manufacturer package insert for azithromycin are:

  • Diarrhea (8.5%)
  • Nausea (6.6%)
  • Abdominal pain (2.7%)
  • Vomiting (1.4%)

While constipation was not reported in initial drug trials of azithromycin, it is a rare occurrence that patients have reported in after market use.  Some possible reasons for this include:

  • A decreased intake of food and water due to sickness
  • Changes in intestinal flora due to antibiotic use
  • Change in normal exercise habits.

Possible Treatments for Constipation

Some possible treatments for constipation due to antibiotic use include dietary changes and over the counter medications.  Over the counter treatment should not be used if there is any rectal bleeding or if there has been a change in bowel habits for 2 weeks or more.  In these cases, your primary care provider should be contacted first.  Otherwise, the following treatments are appropriate.

Initial treatment may be as simple as increasing fiber and fluid (especially water) intake.  When we are sick, our diets tend to change. We may eat a lot less, eat more carbohydrates and stay away from fruits and vegetables.  We also may not be drinking as much as usual.  These changes alone can have an effect on our bowel habits.  The American Dietetic Association recommends 25g and 38g of fiber for women and men respectively daily. Increasing fiber intake by eating fruits and vegetables and other high fiber foods, can help reach these daily amounts. It is especially important when increasing fiber to also increase fluid intake.  

Bulk forming laxatives such as Citrucel and Metamucil can also be used.  They work by creating bulk in the intestines that stimulates the movement of the bowels and aids in elimination. These laxatives typically work in 12-24 hours but can take up to 72 hours to work.  Bulk forming laxatives typically have few side effects when taken as directed.  Flatulence (gas) and abdominal cramping are the most common side effects.  Increasing fluid intake is also important when taking these medications.  Inadequate fluid intake can worsen the constipation.  Dosing of other medications needs to be separated by 2 hours.  Since these agents stay in the gastrointestinal tract, they potentially could interfere with the absorption of other medications.

Docusate sodium is an emollient agent that lubricates the stool and helps with elimination.  Docusate sodium usually works within 12-72 hours but can take up to 3 to 5 days to work.  It is typically a well tolerated medication, but could occasionally cause diarrhea and mild abdominal cramping.  

MiraLAX (polyethylene glycol 3350) is a hyperosmotic agent that works by drawing water into the colon to stimulate a bowel movement.  This usually produces a bowel movement in 12-72 hours, but can take up to 96 hours to work.  This medication is not absorbed systemically and is well tolerated.  Possible side effects may include bloating, flatulence (gas) and abdominal cramping and/or discomfort.  This medication should not be used in patients with known renal disease.

While constipation is a rare reported side effect of taking azithromycin, the above treatments can be used to aid in the relief of constipation.  It should also be noted that though azithromycin may typically be taken for only 3 to 5 days, the drug itself is present in the body for much longer.

The half-life (the amount of time it takes for the amount of the drug in the body to be reduced by half) is quite long at about 68-72 hours for adults.  Side effects may not resolve themselves for an additional 3 to 5 days after stopping the medication.  Any constipation that lasts longer than a week should be discussed with your primary care giver.