trimethoprim
Trimethoprim is an antibiotic that's used to treat urinary tract infections (UTIs). It's available as a tablet that's taken by mouth either once or twice daily. Side effects include skin rash and itching.
What is Trimethoprim?
What is Trimethoprim used for?
How Trimethoprim works
Trimethoprim is a type of antibiotic called an antifolate. It works by stopping bacteria from being able to make a chemical (folic acid) that's needed for them to grow and survive.
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What are the side effects of Trimethoprim?
Common Side Effects
- Rash
- Itching
Other Side Effects
- Stomach pain
- Diarrhea
- Nausea
- Vomiting
- Skin that's sensitive to sunlight (e.g., sunburn)
Serious Side Effects
- Allergic reactions: hives; rash; blisters; swelling of the lips, tongue, or face; trouble breathing
- Infectious diarrhea (C. difficile-related diarrhea): foul-smelling diarrhea, fever, nausea, frequent bowel movements (up to 15 times per day)
Source:Â DailyMed
The following side effects have also been reported
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor or nurse immediately if any of the following side effects occur:
Rare
Abdominal or stomach pain
black, tarry stools
blistering, peeling, or loosening of skin
changes in skin color
chills
cough or hoarseness
dark urine
dizziness
fever with or without chills
general feeling of tiredness or weakness
headache
joint or muscle pain
light-colored stools
loss of appetite
lower back or side pain
pain, tenderness, or swelling of foot or leg
painful or difficult urination
pale skin
rash
red irritated eyes
red skin lesions, often with a purple center
shortness of breath
sores, ulcers, or white spots in mouth or on lips
swollen or painful glands
tightness in chest
unpleasant breath odor
unusual bleeding or bruising
unusual tiredness or weakness
vomiting of blood
yellow eyes or skin
Incidence not known
Abdominal tenderness
back, leg, or stomach pains
bleeding gums
bleeding under the skin
blindness or vision changes
blood in urine or stools
bluish-colored lips, fingernails, or palms
burning, crawling, itching, numbness, painful, prickling, "pins and needles", or tingling feelings
burning of face or mouth
clumsiness or unsteadiness
cloudy urine
confusion
continuing ringing or buzzing or other unexplained noise in ears
convulsions
cracks in the skin
decreased frequency or amount of urine
diarrhea, watery and severe, which may also be bloody
difficulty breathing
difficulty swallowing
dizziness or lightheadedness
fainting spells
general body swelling
general feeling of discomfort or illness
hearing loss
increased blood pressure
increased thirst
indigestion
irregular heartbeat
large, flat, blue or purplish patches in the skin
large, hive-like swelling on 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 hands, feet, or lips
pain or burning while urinating
pains in the stomach, side, or abdomen, possibly radiating to the back
painful knees and ankles
pinpoint red spots on 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
rapid heart rate
red, swollen skin
redness of the white part of the eyes
redness, swelling, or soreness of tongue
shakiness and unsteady walk
soreness of muscles
stiff neck or back
swelling of face, hands, legs, and feet
swelling or inflammation of the mouth
trouble breathing
unsteadiness, trembling, or other problems with muscle control or coordination
unusual weight loss
weakness in hands or feet
weakness or heaviness of legs
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Incidence not known
Discouragement
feeling of constant movement of self or surroundings
feeling sad or empty
increased sensitivity of skin to sunlight
irritability
lack of feeling or emotion
loss of interest or pleasure
nervousness
redness or other discoloration of skin
seeing, hearing, or feeling things that are not there
sensation of spinning
severe sunburn
trouble concentrating
trouble sleeping
unable to sleep
uncaring
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Pros and cons of Trimethoprim
Pros
Available as a lower-cost generic medication
Can use if you have a sulfa allergy
Typically mild and tolerable side effects
Cons
Can make your skin more sensitive to the sun and raise your risk for sunburns
Not the best choice if you're pregnant or breastfeeding because of interactions with folic acid
Might not be the best option if you have kidney problems; might require dose adjustments
Pharmacist tips for Trimethoprim
Take trimethoprim exactly as prescribed. Make sure to finish your treatment course, even if you start feeling better. Stopping the medication earlier than prescribed can make your infection come back and become harder to treat.
Take trimethoprim with or without food. Taking the antibiotic with food might help ease upset stomach if you've experienced this side effect.
Rash and itchiness are the most common side effects from trimethoprim. Talk to a provider if you have these side effects and they become too bothersome.
Trimethoprim can make your skin more sensitive to the sun, which raises your risk for sunburns. To protect your skin, be sure to wear sunscreen when going outside, wear long-sleeved clothing, and avoid being exposed to light or sun for a long time if you can.
Sometimes, trimethoprim can cause diarrhea. It's typically mild and it should go away when you stop taking the antibiotic. But call your provider right away if you start having watery or bloody diarrhea, fever, fatigue, or stomach cramps anytime during treatment or after stopping trimethoprim. These can be signs of serious infectious diarrhea that needs to be treated quickly.
Ask your provider if you should take a probiotic along with trimethoprim. Some research suggests that probiotics might help lower the risk of infectious diarrhea from antibiotics. Make sure to separate any probiotics you take from trimethoprim by at least 2 hours to prevent trimethoprim from killing the "good" bacteria in the probiotic.
Tell your provider if you take phenytoin (Dilantin) because trimethoprim can affect how well phenytoin (Dilantin) gets removed from your body. This drug interaction can raise your risk for side effects from phenytoin (Dilantin).
Make sure to tell your provider if you're pregnant or breastfeeding before using trimethoprim. Studies show that the antibiotic might cause harm to babies during early pregnancy or while breastfeeding. This is because the medication can interfere with chemical pathways in the body that involve folic acid (an important nutrient for growth and development). Trimethoprim should be used only if it's clearly needed if you're pregnant or breastfeeding.
Frequently asked questions about Trimethoprim
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What are the risks and warnings for Trimethoprim?
Trimethoprim can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Serious allergic reactions
Although rare, serious allergic reactions to trimethoprim are possible, including life-threatening reactions like severe skin reactions and anaphylaxis (e.g., closing of the throat). Let your provider know if you have an allergy to antibiotics to make sure trimethoprim is safe for you to take. Get medical attention right away if you notice hives, rash, red skin, peeling or blistering skin, swelling of the lips or tongue, or difficulty breathing after taking trimethoprim.
Diarrhea from Clostridioides difficile infection
Antibiotics, including trimethoprim, raise your risk of getting infected with a bacteria called Clostridioides difficile (C. diff). This infection can cause diarrhea that can sometimes be life-threatening. Antibiotics change the amount of normal bacteria in your stomach and intestines. This can cause C. diff to overgrow in your gut and lead to an infection.
It's important to recognize the difference between diarrhea as a side effect of trimethoprim and this type of infectious diarrhea. C. diff-related diarrhea can cause rapid heart rate, foul-smelling diarrhea, fever, nausea, frequent bowel movements (even up to 15 times per day) and is an emergency. Get medical attention right away if you experience any of these symptoms to get tested for C. diff infection and receive treatment, if needed.
Development of drug-resistant bacteria
Take trimethoprim exactly as prescribed. Taking trimethoprim for any shorter or longer periods of time or taking the antibiotic for other illnesses can raise your risk for developing infections caused by drug-resistant bacteria. This raises your risk for severe and life-threatening infections that might be difficult to treat.
Trimethoprim dosage forms
| Dosage | Quantity | Price as low as | Price per unit |
|---|---|---|---|
| 100mg | 90 tablets | $37.98 | $0.42 |
Typical dosing for Trimethoprim
The typical dose for adults is 100 mg by mouth every 12 hours for 10 days. An alternative dosage is 200 mg by mouth once daily for 10 days.
Your dose might differ if you have kidney problems.
Interactions between Trimethoprim and other drugs
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are receiving this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
- Dofetilide
- Levomethadyl
- Methenamine
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Acecainide
- Acenocoumarol
- Ajmaline
- Amiloride
- Amiodarone
- Amitriptyline
- Amoxapine
- Aprindine
- Arsenic Trioxide
- Astemizole
- Azathioprine
- Azilsartan
- Azilsartan Medoxomil
- Azimilide
- Benazepril
- Bretylium
- Candesartan Cilexetil
- Captopril
- Ceritinib
- Chloral Hydrate
- Chloroquine
- Chlorpromazine
- Cholera Vaccine, Live
- Clarithromycin
- Desipramine
- Dibenzepin
- Digoxin
- Disopyramide
- Dolasetron
- Doxepin
- Dronedarone
- Droperidol
- Enalapril
- Enalaprilat
- Enflurane
- Eplerenone
- Eprosartan
- Erythromycin
- Flecainide
- Fluconazole
- Fluoxetine
- Foscarnet
- Fosinopril
- Gemifloxacin
- Halofantrine
- Haloperidol
- Halothane
- Hydroquinidine
- Ibutilide
- Imipramine
- Irbesartan
- Isoflurane
- Isradipine
- Leucovorin
- Lidoflazine
- Lisinopril
- Lorcainide
- Losartan
- Mefloquine
- Mercaptopurine
- Methotrexate
- Moexipril
- Nortriptyline
- Octreotide
- Olmesartan Medoxomil
- Pentamidine
- Perindopril
- Pirmenol
- Porfimer
- Prajmaline
- Probucol
- Procainamide
- Prochlorperazine
- Propafenone
- Pyrimethamine
- Quinapril
- Quinidine
- Ramipril
- Risperidone
- Sapropterin
- Sematilide
- Sertindole
- Sotalol
- Spiramycin
- Spironolactone
- Sultopride
- Tedisamil
- Telithromycin
- Telmisartan
- Trandolapril
- Triamterene
- Trifluoperazine
- Trimipramine
- Valsartan
- Warfarin
- Zofenopril
- Zotepine
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Acetohexamide
- Amantadine
- Aminolevulinic Acid
- Anisindione
- Didanosine
- Fosphenytoin
- Phenytoin
- Repaglinide
- Rifabutin
- Rosiglitazone
- Tolbutamide
How much does Trimethoprim cost?
Trimethoprim contraindications
Anemia that's caused by folic acid deficiency (low folic acid levels)
What are alternatives to Trimethoprim?
Treatment or prevention of urinary tract infections
Lower respiratory tract infection (e.g., Pneumocystis pneumonia, infections related to bronchitis)
Travelers' diarrhea - tablet or liquid only
Ear infections - tablet or liquid only
Trimethoprim images
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References
Best studies we foundAndersen, J. T., et al. (2013). Trimethoprim use in early pregnancy and the risk of miscarriage: A register-based nationwide cohort study. Epidemiology and Infection.
Estrada, A., et al. (2016). Antibacterial antifolates: From development through resistance to the next generation. Cold Spring Harbor Perspectives in Medicine.
Jancel, T., et al. (2002). Management of uncomplicated urinary tract infections. The Western Journal of Medicine.
MedlinePlus. (2022). Folate-deficiency anemia.
Novitium Pharma LLC. (2022). Trimethoprim tablet [package insert]. DailyMed.
Pharmacist’s Letter. (2023). Meds that should not be crushed.
Wróbel, A., et al. (2020). Trimethoprim and other nonclassical antifolates an excellent template for searching modifications of dihydrofolate reductase enzyme inhibitors. The Journal of Antibiotics.
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