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Trimethoprim

Trimethoprim Side Effects

Robert Chad Hakim, PharmD, BCCCPAllison Gourley, PharmD
Reviewed by Robert Chad Hakim, PharmD, BCCCP, Allison Gourley, PharmD
Last reviewed on September 19, 2023

The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.

Common Side Effects

  • Rash
  • Itching

Less Common Side Effects

  • Stomach pain
  • Diarrhea
  • Nausea
  • Vomiting
  • Skin that's sensitive to sunlight (e.g., sunburn)

Trimethoprim serious side effects

Contact your healthcare provider immediately if you experience any of the following.

  • 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: DailyMed

The following Trimethoprim 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

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 foot or leg

painful or difficult urination

pale skin

rash

red irritated eyes

red skin lesions, often with a purple center

shortness of breath

sore throat

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

wheezing

yellow eyes or skin

Incidence not known

Abdominal tenderness

back, leg, or stomach pains

bleeding gums

bleeding under the skin

blindness or vision changes

blisters, hives, or itching

bloating

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

constipation

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

hair loss

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

scaly skin

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

weight gain

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:

More common

Hives or welts

passing of gas

redness of skin

stomach pain, fullness, or discomfort

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

sleeplessness

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.

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