Trimethoprim Side Effects

Brand Names: Primsol, Proloprim

Please note - some side effects for Trimethoprim may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA at http://www.fda.gov/medwatch/ or 1-800-FDA-1088 (1-800-332-1088).

Side Effects of Trimethoprim - for the Consumer

Trimethoprim

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Trimethoprim:

Nausea; skin sensitivity to sunlight; stomach upset; vomiting.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blistered, peeling, red, or swollen skin; bloody or black, tarry stools; chest pain; chills, fever, or sore throat; decreased urination; joint or muscle pain; irregular heartbeat; painful or stiff neck; purple patches under the skin; seizures; severe diarrhea; shortness of breath; stomach cramps/pain; unusual bruising or bleeding; unusual tiredness or weakness; unusually pale skin; vaginal irritation or discharge; yellowing of the skin or eyes.

Trimethoprim Solution

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Trimethoprim Solution:

Nausea; skin sensitivity to sunlight; stomach upset; vomiting.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blistered, peeling, red, or swollen skin; bloody or black, tarry stools; chest pain; chills, fever, or sore throat; decreased urination; irregular heartbeat; joint or muscle pain; painful or stiff neck; purple patches under the skin; seizures; severe diarrhea; shortness of breath; stomach cramps/pain; unusual bruising or bleeding; unusual tiredness or weakness; unusually pale skin; vaginal irritation or discharge; yellowing of the skin or eyes.

Trimethoprim Side Effects - for the Professional

Trimethoprim

The adverse effects encountered most often with Trimethoprim were rash and pruritus.

Dermatologic

Rash, pruritus, and phototoxic skin eruptions. At the recommended dosage regimens of 100 mg b.i.d. or 200 mg q.d., each for 10 days, the incidence of rash is 2.9% to 6.7%. In clinical studies which employed high doses of Trimethoprim, an elevated incidence of rash was noted. These rashes were maculopapular, morbilliform, pruritic, and generally mild to moderate, appearing 7 to 14 days after the initiation of therapy.

Hypersensitivity

Rare reports of exfoliative dermatitis, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis (Lyell Syndrome), and anaphylaxis have been received.

Gastrointestinal

Epigastric distress, nausea, vomiting, and glossitis. Elevation of serum transaminase and bilirubin has been noted, but the significance of this finding is unknown. Cholestatic jaundice has been rarely reported.

Hematologic

Thrombocytopenia, leukopenia, neutropenia, megaloblastic anemia, and methemoglobinemia.

Metabolic

Hyperkalemia, hyponatremia.

Neurologic

Aseptic meningitis has been rarely reported.

Miscellaneous

Fever, and increases in BUN and serum creatinine levels.

Side Effects by Body System

Hypersensitivity

Hypersensitivity reactions have included diffuse, often pruritic, maculopapular or urticarial rashes (up to 7%), Stevens-Johnson syndrome, exfoliative dermatitis, erythema multiforme, fixed drug eruption, linear fixed drug eruption, toxic epidermal necrolysis, and anaphylaxis.

A Dutch retrospective analysis identified 13 cases of probable or possible anaphylaxis with a probable or definite causal relationship to trimethoprim.

Rare cases of diffuse pneumonitis associated with trimethoprim have been reported.

One case report describes Stevens-Johnson syndrome, arthritis and uveitis associated with trimethoprim.

Dermatologic

The incidence of rash is approximately 2.9% to 6.7% at recommended doses of 200 mg/day.

A higher incidence of rash was reported in clinical trials using large doses of trimethoprim. These rashes had an onset of 7 to 14 days after begin of therapy and were maculopapular, morbilliform, pruritic, and mild to moderate in severity.

Dermatologic side effects have included rash, pruritus, and phototoxic reactions.

Renal

Renal side effects have been uncommon. Trimethoprim may inhibit renal tubular creatinine secretion, resulting in increased serum levels. Some data indicate a significant decrease in creatinine clearance associated with trimethoprim. These changes appear to be completely reversible upon discontinuation of therapy.

Trimethoprim has an aldosterone-antagonistic effect in the renal tubule, which can result in hyperkalemia.

Trimethoprim acts like amiloride and blocks apical membrane sodium channels in the distal nephron. This results in inhibition of potassium secretion and mild hyperkalemia in some cases. Up to 20% of patients with AIDS who are given trimethoprim-sulfamethoxazole develop mild hyperkalemia due to the effect of trimethoprim, not sulfamethoxazole, on the kidney.

Gastrointestinal

Rare cases of Clostridium difficile pseudomembranous colitis have been reported during or after trimethoprim therapy.

Gastrointestinal side effects have included nausea, vomiting, mild abdominal distress, glossitis, and pseudomembranous colitis.

Hematologic

Hematologic side effects have included leukopenia, megaloblastic anemia, methemoglobinemia, neutropenia, and thrombocytopenia.

Since trimethoprim inhibits a step of folate synthesis in vivo, megaloblastic anemia is more likely in patients with folate deficiency, such as alcoholics, the malnourished, and in patients with chronic hemolytic anemia.

Nervous system

Nervous system side effects have included rare reports of aseptic meningitis.

Trimethoprim-induced aseptic meningitis is characterized by a sterile cerebral spinal fluid pleocytosis (usually lymphocytic) associated with meningismus. Trimethoprim-associated aseptic meningitis, like that associated with some nonsteroidal anti-inflammatory medications, may be more likely in patients with underlying connective tissue diseases, such as systemic lupus erythematosus or Sjogren's syndrome. Occult bacterial, viral, and atypical etiologies of meningitis must also be considered. Cases of aseptic meningitis has been reported in AIDS patients.

Metabolic

Metabolic side effects have included hyperkalemia associated with sulfamethoxazole-trimethoprim in elderly patients, and hyponatremia.

Hepatic

Hepatic side effects have included cholestatic jaundice and elevations of serum transaminases and bilirubin.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date, and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This information does not endorse drugs, diagnose patients, or recommend therapy. This drug information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug of drug combination is safe, effective, or appropriate for any given patient. Drugs.com does not assume any responsibility for any aspect of healthcare administered with the aid of information provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse, or pharmacist.