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Cefdinir: 7 things you should know

Medically reviewed by Carmen Fookes, BPharm. Last updated on Aug 29, 2022.

1. How it works

  • Cefdinir is an antibiotic used to treat mild infections caused by susceptible gram-positive and gram-negative bacteria.
  • Cefdinir works by binding to and blocking the activity of enzymes responsible for making peptidoglycan, an important component of the bacterial cell wall. They are called broad-spectrum antibiotics because they are effective against a wide range of bacteria. Cefdinir is bactericidal (kill bacteria) and works in a similar way to penicillin.
  • Cefdinir belongs to the class of antibiotics known as cephalosporins. Cefdinir is a third-generation cephalosporin.

2. Upsides

  • Treats a wide range of mild-to-moderate infections such as those occurring in the respiratory tract, ear, and on the skin, such as community-acquired pneumonia, acute exacerbations of chronic bronchitis, and sinusitis, tonsillitis, or skin infections.
  • Has excellent activity against susceptible gram-positive and gram-negative bacteria, such as Staphylococcus aureus (methicillin-susceptible strains only), Streptococcus pneumoniae (penicillin-susceptible strains only), S. pyogenes, Haemophilus influenzae, H. parainfluenzae, and Moraxella catarrhalis.
  • Stable in the presence of some (but not all) beta-lactamase enzymes.
  • Available as an oral capsule and an oral powder for suspension.
  • May be administered once or twice a day depending on the type of infection.
  • May be taken with or without food.
  • Generic cefdinir is available.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • Diarrhea, rash, and vomiting are the most common side effects. Other side effects may occur but these are generally rare, mild, and resolve with continued therapy.
  • Severe diarrhea, caused by the overgrowth of a bacteria called Clostridium difficile, is a potential side effect of almost all antibacterial agents, including cefdinir. Symptoms include persistent, watery, and sometimes bloody diarrhea.
  • The dosage of cefdinir may need to be reduced in people with markedly compromised kidney function or who are undergoing hemodialysis. Seizures have been reported when cephalosporins have been used in people with impaired kidney function without a dosage reduction.
  • Cross-sensitivity is well documented between cephalosporin and penicillin-type antibiotics. Up to 10% of people who are allergic to penicillin are also allergic to cephalosporins such as cefdinir. Epinephrine and other emergency measures should be on hand if the decision is made to administer cefdinir to a person with a documented penicillin allergy. If a reaction occurs, treat the reaction, discontinue cefdinir, and do not rechallenge.
  • May interact with some drugs including aluminum and magnesium-containing antacids, iron supplements or foods fortified with iron, and probenecid.
  • Studies in people with liver disease have not been conducted but it is expected that a dosage adjustment is not required in this population.
  • May not be suitable for some people including those with kidney disease or colitis. Only effective for certain types of bacterial infection.
  • There are no adequate and well-controlled studies in pregnant women. Only use during pregnancy if clearly needed.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

  • Cefdinir is a cephalosporin-type antibiotic effective at treating mild-to-moderate infections caused by susceptible gram-positive and gram-negative bacteria. Side effects are generally mild but may include diarhea, rash, or vomiting.

5. Tips

  • Store cefdinir suspension at room temperature (68-77°F [20-25°C]), away from moisture and heat and shake well before each administration. Use a measuring spoon to measure the correct dose. Discard any unused portion after 10 days.
  • Do not take if you are allergic to cephalosporin-type antibiotics such as Ceftin, Cefzil, Keflex, and others. Tell your doctor if you are allergic to penicillin, as cross-sensitivity may occur.
  • May be taken with or without food.
  • Do not take at the same time as antacids containing magnesium or aluminum, or supplements containing iron. Separate administration by at least two hours. Note that iron-fortified formula does not significantly interfere with cefdinir suspension and may be administered at the same time.
  • Take cefdinir exactly as prescribed and finish the course to reduce the development of drug-resistant bacteria. Never share your antibiotics with somebody else. Cefdinir only treats bacterial infections, not viral infections.
  • See your doctor if you develop prolonged or significant watery or bloody diarrhea while taking cefdinir or within two months of finishing the course.
  • People with diabetes should be aware that cefdinir suspension contains 2.86g of sucrose per teaspoon. Cefdinir may also interfere with urine glucose or ketone tests.
  • Tell your doctor if you are pregnant or intending to become pregnant before taking cefdinir.

6. Response and effectiveness

  • Cefdinir reaches a peak level in the blood within two to four hours of taking an oral capsule.

7. Interactions

Medicines that interact with cefdinir may either decrease its effect, affect how long it works for, increase side effects, or have less of an effect when taken with cefdinir. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with cefdinir include:

  • antacids containing aluminum or magnesium
  • anticoagulants (blood thinners), such as warfarin (may prolong bleeding time)
  • estradiol
  • iron supplements or foods fortified with iron
  • other antibiotics, such as chloramphenicol, sulfonamides, macrolides, and tetracycline
  • probenecid
  • probiotics, such as Lactobacillus
  • vaccinations, such as BCG, cholera, or typhoid vaccine (may diminish the effectiveness)
  • vitamins, such as fat-soluble vitamins A, D, E, or K, folate, iron, or zinc (may decrease blood concentrations of cefdinir)
  • warfarin.

May cause a false-positive for ketones in the urine with tests that use nitroprusside but not with those using nitroferricyanide. False-positive results for glucose in the urine may also occur with Clinitest, Benedict's solution, or Fehling's solution. Use tests that are based on enzymatic glucose oxidase reactions, such as Clinistix or Tes-Tape instead.

Note that this list is not all-inclusive and includes only common medications that may interact with cefdinir. You should refer to the prescribing information for cefdinir for a complete list of interactions.


Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use cefdinir only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Copyright 1996-2023 Revision date: August 28, 2022.