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Last reviewed on RxList: 5/8/2018
Bactrim Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

Last reviewed on RxList 5/8/2018

Bactrim (sulfamethoxazole and trimethoprim) DS is a combination of two antibiotics used to treat urinary tract infections, acute otitis media, bronchitis, Shigellosis, Pneumocystis pneumonia, traveler's diarrhea, methicillin-resistant Staphylococcus aureus (MRSA), and other bacterial infections susceptible to this antibiotic. Bactrim is available as a generic drug. Common side effects of Bactrim include:

Tell your doctor if you experience serious side effects of Bactrim including:

Bactrim is available in tablets in two strengths; 400 mg sulfamethoxazole and 80 mg trimethoprim and the "DS" form which means double strength, 800 mg sulfamethoxazole and 160 mg trimethoprim. Patients should follow their doctor's instructions and take all of the Bactrim prescribed. Patients allergic to sulfa compounds should not take Bactrim. Bactrim may interact with many drugs; the patient and prescribing doctor should be aware of any potential interactions. Bactrim should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus; the same situation exists for women who are breastfeeding and their neonates.

Our Bactrim DS Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Bactrim Consumer Information

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • diarrhea that is watery or bloody;
  • pale skin, feeling light-headed or short of breath, rapid heart rate, trouble concentrating;
  • sudden weakness or ill feeling, fever, chills, sore throat, new or worsening cough;
  • cold or flu symptoms, swollen gums, painful mouth sores, pain when swallowing, skin sores;
  • low levels of sodium in the body--headache, confusion, slurred speech, severe weakness, vomiting, loss of coordination, feeling unsteady;
  • liver problems--upper stomach pain, tired feeling, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); or
  • severe skin reaction--fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Common side effects may include:

  • nausea, vomiting, loss of appetite; or
  • mild itching or rash.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Bactrim (Trimethoprim and Sulfamethoxazole)

Bactrim Professional Information


The following serious adverse reactions are described elsewhere in the labeling:

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The most common adverse reactions are gastrointestinal disturbances (nausea, vomiting, and anorexia) and allergic skin reactions (such as rash and urticaria).

Local reaction, pain and slight irritation on intravenous (IV) administration are infrequent. Thrombophlebitis has been observed.

Table 3: Adverse Reactions Reported with BACTRIM

Body System Adverse Reactions
  • Agranulocytosis
  • Aplastic anemia
  • Thrombocytopenia
  • Leukopenia
  • Neutropenia
  • Hemolytic anemia
  • Megaloblastic anemia
  • Hypoprothrombinemia
  • Methemoglobinemia
  • Eosinophilia
Allergic Reactions
  • Stevens-Johnson syndrome
  • Toxic epidermal necrolysis
  • Anaphylaxis
  • Allergic myocarditis
  • Erythema multiforme
  • Exfoliative dermatitis
  • Angioedema
  • Drug fever
  • Chills
  • Henoch-Schoenlein purpura
  • Serum sickness-like syndrome
  • Conjunctival and scleral injection
  • Photosensitivity
  • Pruritus
  • Urticaria
  • Rash
  • Periarteriitis nodosa
  • Systemic lupus erythematosus
  • Hepatitis (including cholestatic jaundice and hepatic necrosis)
  • Elevation of serum transaminase and bilirubin
  • Pseudomembranous enterocolitis
  • Pancreatitis
  • Stomatitis
  • Glossitis
  • Nausea
  • Emesis
  • Abdominal pain
  • Diarrhea
  • Anorexia
  • Renal failure
  • Interstitial nephritis
  • BUN and serum creatinine elevation
  • Toxic nephrosis with oliguria and anuria
  • Crystalluria
Metabolic and Nutritional
  • Hyperkalemia
  • Hyponatremia [see WARNINGS AND PRECAUTIONS]
  • Aseptic meningitis
  • Convulsions
  • Peripheral neuritis
  • Ataxia
  • Vertigo
  • Tinnitus
  • Headache
  • Hallucinations
  • Depression
  • Apathy
  • Nervousness
  • Sulfonamides bear certain chemical similarities to some goitrogens, diuretics (acetazolamide and the thiazides) and oral hypoglycemic agents (cross-sensitivity may exist with these agents)
  • Diuresis and hypoglycemia (have occurred in patients receiving sulfonamides)
  • Arthralgia
  • Myalgia
  • Rhabdomyolysis
  • Cough
  • Shortness of breath
  • Pulmonary infiltrates
  • Weakness
  • Fatigue
  • Insomnia
Eye Disorders
  • Uveitis5

Postmarketing Experience

The following adverse reactions have been identified during post-approval use of BACTRIM. Because these reactions were reported voluntarily from a population of uncertain size, it is not possible to reliably estimate their frequency or establish a causal relationship to drug exposure:

Read the entire FDA prescribing information for Bactrim (Trimethoprim and Sulfamethoxazole)

Related Resources for Bactrim

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