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Sulfamethoxazole/Trimethoprim

Sulfamethoxazole/Trimethoprim Side Effects

Robert Chad Hakim, PharmD, BCCCPCydnee Ng, PharmD
Reviewed by Robert Chad Hakim, PharmD, BCCCP, Cydnee Ng, PharmD
Last reviewed on May 16, 2024

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

Less Common Side Effects

  • Muscle pain
  • Joint pain
  • Fatigue
  • Weakness
  • Trouble falling asleep
  • Changes to blood sugar levels

Sulfamethoxazole/Trimethoprim serious side effects

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

  • Serious allergic reaction or skin reaction: hives, rash, blisters, skin reddening, swelling of the lips or tongue, difficulty breathing
  • Infectious diarrhea (C. difficile-related diarrhea): rapid heart rate, fever, nausea, foul-smelling diarrhea, frequent bowel movements (even up to 15 times per day)
  • High potassium levels: nausea, muscle cramps or weakness
  • Low sodium levels: nausea, fatigue, headache, confusion, hallucinations (seeing things that aren't real), seizure, unconsciousness
  • Kidney problems: urinating less often than usual; swelling in your feet, ankles, or hands; unexplained weight gain
When do Sulfamethoxazole/Trimethoprim possible side effects begin and end?
Time passed since treatment started:
M
H
D
W
M
Nausea or vomiting
Stomach upset
Skin sensitivity to sun (risk for sunburn)
Skin rash
Seek immediate medical care if you experience this side effect.

Source: DailyMed

The following Sulfamethoxazole/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 immediately if any of the following side effects occur:

More common

Black, tarry stools

blistering, peeling, or loosening of the skin

changes in skin color

chest pain or tightness

chills

cough or hoarseness

dark urine

diarrhea

dizziness

fever

general feeling of tiredness or weakness

headache

itching, skin rash

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

red skin lesions, often with a purple center

red, irritated eyes

sore throat

sores, ulcers, or white spots in the mouth or on the lips

stomach pain

swollen or painful glands

trouble breathing

unpleasant breath odor

unusual bleeding or bruising

vomiting of blood

yellow eyes or skin

Incidence not known

Back, leg, or stomach pains

bleeding gums

blindness or vision changes

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

cloudy urine

confusion

constipation

continuing ringing or buzzing or other unexplained noise in the ears

cracks in the skin

decreased frequency or amount of urine

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

seizures

soreness of the muscles

stiff neck or back

stomach tenderness

swelling of the face, hands, legs, and feet

unsteadiness, trembling, or other problems with muscle control or coordination

weakness in the hands or feet

weakness or heaviness of the legs

weight gain or loss

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

Passing of gas

Incidence not known

Discouragement

feeling of constant movement of self or surroundings

feeling sad or empty

increased sensitivity of the skin to sunlight

lack of feeling or emotion

loss of interest or pleasure

nervousness

redness or other discoloration of the skin

seeing, hearing, or feeling things that are not there

sensation of spinning

severe sunburn

trouble concentrating

trouble sleeping

uncaring

weight loss

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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