Update Date 06/05/2020 . 7 mins read
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Know the basics

What is Bactrim (Sulfamethoxazole and Trimethoprim) used for?

Bactrim is an antibiotic combination, commonly used for treat infections, including:

  • Urinary tract infections;
  • Middle ear infections (otitis media);
  • Bronchitis;
  • Traveler’s diarrhea;
  • Shigellosis (bacillary dysentery).

Bactrim can be used to prevent or treat pneumonia caused by infection of Pneumocystis jiroveci or Pneumocystis carinii pneumonia (PCP).

How should I take Bactrim (Sulfamethoxazole and Trimethoprim)?

For orally taken form, you should:

  • Take Bactrim by mouth as directed by your doctor concerning: dose, schedule.
  • Read the label carefully before using Bactrim.
  • Consult your doctor for any information on the label that you do not clearly understand.

How do I store Bactrim (Sulfamethoxazole and Trimethoprim)?

Bactrim is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store Bactrim in the bathroom or the freezer. There may be different brands of Bactrim that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush Bactrim down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Know the precautions & warnings

What should I know before using Bactrim (Sulfamethoxazole and Trimethoprim)?

Before using Bactrim, tell your doctor if you have:

  • Allergic reaction: to Bactrim, excipients using for a dosage form containing Bactrim. The information is detailed in the leaflet.
  • Allergic reaction to any other medicines, foods, dyes, preservatives, or animals.
  • Pediatric.
  • Geriatric.
  • Used any other health conditions, drugs that have a risk of interaction with Bactrim as listed below.

Is it safe during pregnancy or breastfeeding?

Please always consult with your doctor to weigh the potential benefits and risks before taking Bactrim. Bactrim is pregnancy risk category D according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk;
  • B=No risk in some studies;
  • C=There may be some risk;
  • D=Positive evidence of risk;
  • X=Contraindicated;
  • N=Unknown.

There is evidence that suggests that this drug can cause adverse effects to the fetus. This drug should not be taken unless prescribed by a doctor.

Know the side effects

What side effects can occur from Bactrim (Sulfamethoxazole and Trimethoprim)?

As taking others medicines, taking Bactrim can cause some side effects. Most of them are rarely occurring and do not need any supplementary treatment. However, it is always important for you to consult your doctor if you have any problem after taking this medicine.

Some of the side effects are listed below: :

Abdominal or stomach pain; black, tarry stools; blistering, peeling, or loosening of the skin; changes in skin color; chest pain; chills; cough or hoarseness; dark urine; diarrhea; dizziness; fever with or without chills; general feeling of tiredness or weakness; headache; itching; joint or muscle pain; light-colored stools; loss of appetite; lower back or side pain; nausea; pain, tenderness, or swelling of the foot or leg; painful or difficult urination; pale skin; rash; red skin lesions, often with a purple center; red, irritated eyes; shortness of breath; sore throat; sores, ulcers, or white spots in the mouth or on the lips; swollen or painful glands; tightness in the chest; unpleasant breath odor; unusual bleeding or bruising; vomiting of blood; wheezing; yellow eyes or skin.

Abdominal or stomach tenderness; back, leg, or stomach pains; bleeding gums; blindness or vision changes; blisters, hives, or itching; bloating; blood in the urine or stools; bluish-colored lips, fingernails, or palms; burning, crawling, itching, numbness, painful, prickling, “pins and needles”, or tingling feelings; burning of the face or mouth; chest pain; cloudy urine; confusion; constipation; continuing ringing or buzzing or other unexplained noise in the ears; convulsions; cracks in the skin; decreased frequency or amount of urine; diarrhea, watery and severe, which may also be bloody; difficulty with breathing; difficulty with swallowing; fainting spells; general body swelling; general feeling of discomfort or illness; hair loss; hearing loss; hives; increased thirst; indigestion; irregular heartbeat; large, flat, blue, or purplish patches in the skin; large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs; loss of heat from the body; muscle or joint pain; nosebleeds; not able to pass urine; numbness or tingling in the hands, feet, or lips; pain or burning while urinating; pinpoint red spots on the skin; puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue; raised red swellings on the skin, the buttocks, legs, or ankles; redness of the white part of the eyes; redness, swelling, or soreness of the tongue; sores, ulcers, or white spots on the lips or in the mouth; soreness of the muscles; stiff neck or back; swelling of the face, hands, legs, and feet; unsteadiness, trembling, or other problems with muscle control or coordination; unusual weight loss; weakness in the hands or feet; weakness or heaviness of the legs; weight gain.

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.

Know the interactions

What drugs may interact with Bactrim (Sulfamethoxazole and Trimethoprim)?

Bactrim may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval, such as:


Levomethadyl; Methenamine; Acecainide; Acenocoumarol; Ajmaline;


Amiodarone; Amisulpride; Amitriptyline; Amoxapine;


Arsenic Trioxide; Astemizole;



Azilsartan Medoxomil; Azimilide;



Candesartan Cilexetil; Captopril;


Chloral Hydrate; Chloroquine; Chlorpromazine; Clarithromycin; Dabrafenib;







Rosiglitazone; Tolbutamide;

Dibenzepin; Disopyramide; Dolasetron;








Eprosartan; Erythromycin;






Gemifloxacin; Halofantrine; Haloperidol;

Halothane; Hydroquinidine; Ibutilide;










Mefloquine; Mercaptopurine; Methotrexate;




Olmesartan Medoxomil; Pentamidine;





Procainamide; Prochlorperazine; Propafenone; Pyrimethamine; Quinapril;







Spiramycin; Spironolactone; Sultopride;


Telithromycin; Telmisartan; Trandolapril; Triamterene; Trifluoperazine; Trimipramine;






Acetohexamide; Amantadine;



Does food or alcohol interact with Bactrim (Sulfamethoxazole and Trimethoprim)?

Bactrim may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with Bactrim (Sulfamethoxazole and Trimethoprim)?

Bactrim may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.

  • Alcohol abuse;
  • Folate (vitamin B9) deficiency;
  • HIV or AIDS;
  • Kidney disease;
  • Liver disease;
  • Malabsorption syndrome (difficulty of absorbing food in the body);
  • Malnutrition state (nutrition disorder);
  • Anemia, megaloblastic (caused by low levels of folic acid in the body);
  • Drug-induced thrombocytopenia (low platelets in the blood) after using this medicine;
  • Kidney disease, severe;
  • Liver disease, severe;
  • Asthma;
  • Diabetes ;
  • Hyperkalemia (high potassium in the blood);
  • Hyponatremia (low sodium in the blood);
  • Porphyria (enzyme problem);
  • Severe allergies;
  • Thyroid problems;
  • Glucose-6-phosphate dehydrogenase (G6PD) deficiency;
  • Streptococcal infection (group A β-hemolytic).

Understand the dosage

The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using Bactrim.

What is the dose of Bactrim (Sulfamethoxazole and Trimethoprim) for an adult?

Consult your doctor for information about the dose of Bactrim hydrochloride.

Urinary Tract Infections and Shigellosis in Adults:

The usual adult dosage in the treatment of urinary tract infections is 1 BACTRIM DS (double strength) tablet or 2 BACTRIM tablets every 12 hours for 10 to 14 days. An identical daily dosage is used for 5 days in the treatment of shigellosis.

For Patients with Impaired Renal Function:

CrCl (mL/min) >30: normal dose; CrCl 15-30: 50% normal dose; CrCl <15: not recommended for use.

Acute Exacerbations of Chronic Bronchitis in Adults:

The usual adult dosage in the treatment of acute exacerbations of chronic bronchitis is 1 BACTRIM DS (double strength) tablet or 2 BACTRIM tablets every 12 hours for 14 days.

Pneumocystis Jiroveci Pneumonia:

The recommended dosage for treatment of patients with documented Pneumocystis jiroveci pneumonia is 75 to 100 mg/kg sulfamethoxazole and 15 to 20 mg/kg trimethoprim per 24

Traveler’s Diarrhea in Adults:

For the treatment of traveler’s diarrhea, the usual adult dosage is 1 BACTRIM DS (double strength) tablet or 2 BACTRIM tablets every 12 hours for 5 days. hours given in equally divided doses every 6 hours for 14 to 21 days.

What is the dose of Bactrim (Sulfamethoxazole and Trimethoprim) for a child?

Consult your doctor for information about the dose of Bactrim hydrochloride.

Urinary Tract Infections, Shigellosis, and Acute Otitis Media in Children:

The recommended dose for children with urinary tract infections or acute otitis media is 40 mg/kg sulfamethoxazole and 8 mg/kg trimethoprim per 24 hours, given in two divided doses every 12 hours for 10 days. An identical daily dosage is used for 5 days in the treatment of shigellosis. The following is a guideline for the attainment of this dosage:

For children >2 months:

  • Weight (in pounds): <44 lbs: not recommended for use; 44-66 lbs.: 1 tablet every 12 hours; 66-88 lbs: 1.5 tablets every 12 hours; 88 lbs and higher: 2 or 1 DS tablet every 12 hours.

For treatment of Pneumocystis jiroveci pneumonia or Pneumocystis carinii pneumonia (PCP):

  • Children aged more than 2 months, the dose is calculated based on body weight and must be determined by your doctor. The usual dose is 75 to 100 milligrams (mg) per kilogram of body weight of sulfamethoxazole and 15 to 20 milligrams (mg) per kilogram of body weight of trimethoprim each day, given in equally divided doses every 6 hours for 14 to 21 days.
  • Children younger than 2 months of age the use of Bactrim is not recommended.

For traveler’s diarrhea:

  • Children 2 months of age and older: use and dose must be determined by your doctor.
  • Children younger than 2 months of age: the use of Bactrim is not recommended.

The dosage has not been established in pediatric patients. It may be unsafe for your child. It is always important to fully understand the safety of the drug before using. Please consult with your doctor or pharmacist for more information.

How is Bactrim (Sulfamethoxazole and Trimethoprim) available?

Bactrim is available in the following dosage forms and strengths:

  • Tablet of 400 mg sulfamethoxazole and 80 mg of trimethoprim.
  • Forte tablet: 800 mg SMZ and 160 mg TMP
  • Syrup: 200 mg SMZ and 40 mg TMP per 5mL

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services (115) or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of Bactrim, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Generic name of this drug: Sulfamethoxazole and Trimethoprim aka Co-trimoxazole

Hello Health Group does not provide medical advice, diagnosis or treatment.

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