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Last reviewed on RxList: 3/16/2017
Bactrim Side Effects Center
Fungal Infections: Fungus Among Us

Medical Editor: John P. Cunha, DO, FACOEP

Last reviewed on RxList 03/10/2017

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:

  • loss of appetite,
  • nausea,
  • vomiting,
  • painful or swollen tongue,
  • dizziness,
  • spinning sensation,
  • ringing in your ears,
  • tiredness, or
  • sleep problems (insomnia).

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
Fungal Infections: Fungus Among Us

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 a serious side effect such as:

  • diarrhea that is watery or bloody;
  • fever, chills, swollen glands, body aches, flu symptoms, sores in your mouth and throat;
  • new or worsening cough;
  • pale skin, feeling light-headed, rapid heart rate, trouble concentrating;
  • easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin;
  • severe tingling or numbness, slow heart rate, weak pulse, muscle weakness;
  • nausea, upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);
  • urinating less than usual or not at all;
  • hallucinations, seizure (convulsions);
  • low blood sugar (headache, hunger, weakness, sweating, confusion, irritability, or feeling jittery);
  • the first sign of any skin rash, no matter how mild; 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.

Less serious side effects may include:

  • vomiting;
  • painful or swollen tongue;
  • dizziness, spinning sensation;
  • ringing in your ears; or
  • tired feeling, sleep problems (insomnia).

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
Fungal Infections: Fungus Among Us


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)

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