Sulfonamide (Oral)

Developed under various brand names, Sulfonamide drugs are used to treat various types of infections and intestinal conditions.


Known collectively as 'sulfa drugs', Sulfonamides are predominantly classified as antibiotics. Originally used in the 1930s, Sulfonamide is still effective in treating bacterial infections. In order to replicate, human cells rely on folic acid. When infections are present, however, bacteria also uses folic acid to divide, replicate and spread.

By inhibiting folate, or folic acid, Sulfonamide prevents the bacteria from replicate and, therefore, stops the infection from spreading further. Folate relies, in part, on an enzyme known as dihydropteroate synthase (DHPS) and it is this enzyme which is affected by Sulfonamide. The medicine binds and inhibits DHPS, thus preventing folate from being synthesized in the body.

Once the production of folate has been affected by Sulfonamide, the bacterial infection can no longer use the body's folic acid to replicate. As a result, the infection will recede, symptoms will lesson and the patient will recover.

Often used in conjunction with other medications, Sulfonamide can be used to treat various different types of bacterial infections, including infections of the bladder, urinary tract, ears, lungs and eyes. Sulfonamide has also been used in the successful treatment of bacterial meningitis, although additional drugs are required for comprehensive treatment to be effective.

Although Sulfonamide works well in treating bacterial infections, it will not resolve viral and/or fungal infections. Due to this, common colds or flu are not usually treated with this type of medication.

Like any antibiotic, Sulfonamide can be ineffective if bacteria develops a resistant to it. In these instances, patients may need an alternative or additional antibiotic. In most cases, however, Sulfonamide is an effective form of treatment for bacterial infections.

As well as being prescribed to treat acute bacterial infections, Sulfonamides can also be used to manage conditions, such as ulcerative colitis. Although ulcerative colitis is a chronic condition, Sulfonamide and Sulfonamide derivatives can be used to relieve symptoms and prevent the disease from worsening. Shown to reduce inflammation and heal mucosal ulcerations in some patients, the medication can be a viable form of symptoms management for patients with on-going intestinal problems.

Although Sulfonamide is usually prescribed on a short-term basis when treating acute infections, patients can take Sulfonamide for long periods of time if it is necessary to do so. Due to this, Sulfonamide is appropriate for managing long-term diseases and conditions, such as irritable bowel disorder, Crohn's colitis and ulcerative colitis.

Perhaps because of its varied uses and low production costs, Sulfonamide has been a drug of choice for many years. The fact that Sulfonamide is effective when used in isolation and when used in conjunction with other drugs simply means that it can be used to treat an ever-increasing list of infections and conditions.

Conditions Treated

Bacterial infections

  • Intestinal disorders, including ulcerative colitis, Crohn's colitis and irritable bowel disorder

Type of Medicine

  • Antibiotic

Side Effects

Like all medications, Sulfonamide has been linked to some side-effects. Although patients may develop unwanted side-effects when taking this medication, this does not mean that the treatment will be ineffective. In fact, Sulfonamide can work well despite the presence of side-effects.

When taking Sulfonamide, patients may experience a range of side-effects. In most cases, these side-effects will be relatively mild and will not require medical intervention. As the medication begins to take effect, the side-effects will often resolve without the need for further or additional treatment. Common side-effects associated with this medication include:

In some cases, however, the presence of certain side-effects may warrant medical attention. If patients exhibit the following side-effects when taking Sulfonamide, they should seek assistance from their physician:

  • Abdominal or stomach cramps and pain
  • Pale skin
  • Blood in urine
  • Diarrhea
  • Sore throat and fever
  • Difficulty in swallowing
  • Lower back pain
  • Mood or mental changes
  • Unusual bleeding or bruising
  • Swelling of front part of neck
  • Aching of joints and muscles
  • Increased thirst
  • Abdominal tenderness
  • Redness, blistering, peeling, or loosening of skin
  • Greatly increased or decreased frequency of urination or amount of urine
  • Pain or burning while urinating
  • Unusual tiredness or weakness
  • Yellow eyes or skin

Depending on the severity of the side-effects, doctors may advise the patient to continue taking Sulfonamide. Similarly, physicians may alter the dose of Sulfonamide if certain side-effects become apparent. As the side-effects listed above could indicate a problem with the absorption of the medication, however, it is important that patients seek medical advice if they develop any of these side-effects when taking Sulfonamide.

As well as discussing their side-effects with their physician, patients may also want to report their side-effects to the Food and Drug Administration. The FDA uses patient reports to compile comprehensive data regarding the side-effects of medications. By contacting them on 1-800-FDA-1088, patients can report their side-effects and contribute to the understanding and development of the drug.


When taking sulfa drugs, it's important that patients adhere to their doctor's instructions. Although standard doses of Sulfonamide are often used, every patient is unique and their treatment and dosage may vary.

It's also important to recognize that different forms of Sulfonamide warrant different doses. Patients should ensure they understand the strength of the medication they are taking and what their dosage instructions are. If patients are unsure how to take the medication or when to take their next dose, they should seek advice from a medical professional, such as their doctor or pharmacist.

The standard dose of Sulfonamide depends on the strength of the medication and the format the medicine is prescribed as. For Sulfadiazine in tablet dose, adult patients are usually given a starting dose of 2-4g, followed by 1g every 4-6 hours. If children are prescribed this medication, they are typically given a lower starting dose of 75mg per kg of body weight, followed by 37.5mg per kg of body weight every 6 hours. Alternatively, children may be given a follow up dose of 25mg per kg of body weight every 4 fours.

If Sulfonamide is prescribed as Sulfamethizole, adult patients and teenagers are usually given 500mg-1g every 6-8 hours, whilst children are generally prescribed 7.5-11.25mg per kg of body weight every 6 hours.

Alternatively, when given as Sulfamethoxazole tablet, physicians will usually prescribe 2-4g as a starting dose and subsequent doses of 1-2g every 8 hours. This is generally accepted to be an appropriate starting dose for otherwise healthy adults and teenager. If prescribed to children, however, a dose of 75mg per kg of bodyweight is generally given as the starting dose, followed by doses of 25mg per kg of body weight every 4 hours or 37.5mg per kg of body weight every 6 hours.

If physicians feel it is more appropriate to prescribe Sulfonamide as syrup or in suspension format, they will often prescribe Sulfisoxazole. This medication can also be prescribed in tablet form, however. Typically, adults and teenagers should take 2-4g as their first dose, followed by 750mg-1.5mg every 4 hours or 1-2mg every 6 hours. When given to children, physicians will often prescribe a dose of 75mg per kg of bodyweight and then subsequent doses of 25mg per kg of body weight every 4 hours or 37.5mg per kg of body weight every 6 hours.

In most cases, patients should take Sulfonamide with a glass of water. In addition to this, patients should drink additional glasses of water throughout the day, unless their doctor has advised against this. Staying well hydrated and consuming an appropriate amount of water can help to prevent side-effects occurring when patients are taking Sulfonamide or a Sulfonamide derivative.

If patients are prescribed medication in liquid form, such as a syrup or solution, they should use a medicine measuring spoon in order to make sure they are taking the right dose. Standard household teaspoons or tablespoons are unlikely to hold the right amount of medication and patients could, therefore, miscalculate the amount of medication they're taking. If the medication is not prescribed with a dedicated measuring spoon, patients can obtain the equipment from their pharmacist.

Typically, Sulfonamide is most effective when a constant amount of medication is present in the patient's body. Due to this, patients should aim to take their dose of medication at evenly spaced times, unless they are directed otherwise.

If a dose of Sulfonamide is missed, patients should take the dose as soon as they remember to do so. If their next dose of medicine is due soon, however, the missed dose will need to be skipped. Patients should not take double doses of Sulfonamide unless their doctor advises them to do so.

If patients are unsure how to take their medication or if they have missed a dose of medicine and are unsure how to proceed with treatment, they should seek advice from their doctor or pharmacist.

As with any antibiotic, it is important that patients finish the course of treatment unless they are directed otherwise by a medical professional. Whilst the infection may begin to dissipate and symptoms may resolve themselves whilst taking Sulfonamide, patients should still take the medication as they have been directed to. Failure to do so can lead to increased antibiotic resistance so it's important that patients understand the need to take their medication as directed.

Potential drug interactions

When more than one drug is consumed, patients may find that they interact with each other. These interactions can have various implications, however, so it does not always prevent Sulfonamide from being used.

If patients are taking any of the following drugs, treatment with Sulfonamide is not normally advisable:

  • Dofetilide
  • Levomethadyl
  • Ketorolac
  • Methenamine

Due to this, physicians may prescribe an alternative antibiotic or advise the patient to cease taking other medications whilst they're receiving antibiotic treatment.

Whilst the following medicines can also interact with Sulfonamide, this does not normally mean that the drugs cannot be taken together:

  • Acenocoumarol
  • Warfarin
  • Amiodarone
  • Amitriptyline
  • Clonixin
  • Amphetamine
  • Amtolmetin Guacil
  • Azimilide
  • Arsenic Trioxide
  • Astemizole
  • Azathioprine
  • Aprindine
  • Bretylium
  • Ceritinib
  • Bufexamac
  • Calcifediol
  • Celecoxib
  • Bromfenac
  • Chloral Hydrate
  • Digitalis
  • Chlorpromazine
  • Cholera Vaccine, Live
  • Enflurane
  • Amoxapine
  • Desipramine
  • Dexibuprofen
  • Doxepin
  • Dibenzepin
  • Diclofenac
  • Chloroquine
  • Acecainide
  • Dipyrone
  • Disopyramide
  • Etodolac
  • Dexketoprofen
  • Droperidol
  • Droxicam
  • Clarithromycin
  • Erythromycin
  • Dolasetron
  • Etofenamate
  • Fluoxetine
  • Felbinac
  • Fenoprofen
  • Halothane
  • Feprazone
  • Flecainide
  • Ibuprofen
  • Fluconazole
  • Flufenamic Acid
  • Etoricoxib
  • Flurbiprofen
  • Foscarnet
  • Aceclofenac
  • Gemifloxacin
  • Halofantrine
  • Haloperidol
  • Fepradinol
  • Hydroquinidine
  • Floctafenine
  • Ibutilide
  • Imipramine
  • Indomethacin
  • Ketoprofen
  • Oxaprozin
  • Isoflurane
  • Leucovorin
  • Levomethadyl
  • Octreotide
  • Lorcainide
  • Lornoxicam
  • Mefanemic Acid
  • Lumiracoxib
  • Meclofenamate
  • Loxoprofen
  • Mefloquine
  • Meloxicam
  • Naproxen
  • Mercaptopurine
  • Methotrexate
  • Orlistat
  • Nabumetone
  • Memantine
  • Nepafenac
  • Niflumic Acid
  • Parecoxib
  • Nimesulide Beta Cyclodextrin
  • Nortriptyline
  • Lidoflazine
  • Morniflumate
  • Isradipine
  • Oxyphenbutazone
  • Nimesulide
  • Pentamidine
  • Phenylbutazone
  • Propafenone
  • Pirmenol
  • Piroxicam
  • Acemetacin
  • Prajmaline
  • Probucol
  • Risperidone
  • Prochlorperazine
  • Proglumetacin
  • Sotalol
  • Propyphenazone
  • Tolmetin
  • Riluzole
  • Pyrimethamine
  • Sertindole
  • Proscillaridin
  • Procainamide
  • Rofecoxib
  • Sematilide
  • Quinidine
  • Piketoprofen
  • Tedisamil
  • Sulindac
  • Sultopride
  • Spiramycin
  • Telithromycin
  • Tenoxicam
  • Vasopressin
  • Tolfenamic Acid
  • Proquazone
  • Valdecoxib
  • Trimipramine
  • Trifluoperazine
  • Tiaprofenic Acid
  • Ajmaline
  • Zotepine

If patients are taking any of the above medications, their doctor may still choose to treat them with Sulfonamide. They may, however, vary the doses of their medications or advise that they be taken at different times of the day.

When two or more medications interact, it's possible for more side-effects to occur or for the severity of side-effects to increase. If patients are concerned about the presence of side-effects or if side-effects are particularly severe, they should seek medical advice.

When taking a prescribed medication, it isn't just other prescription drugs which can cause an interaction to occur. Over-the-counter medications, recreational drugs, alcohol, vitamins, supplements and even some foods can cause drug interactions to occur. Due to this, patients should inform their doctor if they are taking any other medications or substances prior to taking Sulfonamide. By doing so, they can ensure that it's safe for them to take the medication and that it's the most appropriate treatment for them.


If patients have any other medical condition, it may affect the suitability of Sulfonamide as a treatment. Patients who have been diagnosed with liver disease may experience more side-effects when taking Sulfonamide, for example.

If patients have been diagnosed with the following conditions, they should discuss this with their doctor before taking Sulfonamide:

  • Porphyria
  • Kidney disease
  • Liver disease
  • Anemia
  • Glucose-6-phosphate dehydrogenase (G6PD) deficiency

Whilst the presence of these conditions won't necessarily mean that Sulfonamide cannot be used, doctors may monitor patients more carefully or use an alternative dose if these conditions are present.

Although Sulfonamide is normally prescribed for a relatively short-term in the treatment of bacterial infections, patients should expect to see their symptoms reduce within a few days of taking the medication. If they do not, patients may want to consult with their doctor.

If patients are taking Sulfonamide on a long-term basis, such as in the management of intestinal disorders, they should attend regular appointments with their doctor. Long-term use of the medicine has been associated with certain blood problems. By having regular consultations, patients can confirm that the drug is working and that it is not having any harmful effects.

When taking Sulfonamide, patients may notice that they bleed more easily. Bleeding gums are often the first sign that the medication is affecting the blood. Slow healing and an increased chance of infections can also arise because of blood problems caused by Sulfonamide. Due to this, surgery and dental procedures should be avoided whilst the patient is taking Sulfonamide.

Once treatment has been completed, the patient's blood count should increase again and issues, such as slow healing or bleeding gums, should be resolved.

When taking Sulfonamide or a Sulfonamide derivative, patients may notice that their skin is more sensitive to light. A skin rash, severe sunburn, itching, redness and skin discoloration may occur if the patient is exposed to sunlight, even for a relatively brief period of time.

In order to avoid any complications caused by exposure to sunlight, patients should stay out of direct sunlight. It's particularly important that patients stay out of the sun during the hours of 10am-3pm as this is when the sun is at its strongest.

Wearing protective clothing, long sleeves, a hat and sunglasses can also limit the effect of sunlight on the patient's skin. In addition to this, patients may want to use sunblock or a sun lotion with a high SPF when they're taking Sulfonamide. Patients should also avoid using tanning beds and sunlamps whilst taking this medication.

As dizziness is a common side-effect of Sulfonamide, patients need to be aware of how this can affect them. If they develop dizziness, for example, they should not drive or operate heavy machinery until they feel well enough to do so.

In most instances, Sulfonamide should not be prescribed to pregnant or breastfeeding women. The medication may cause bilirubin in the baby's blood to be displaced and this could lead to jaundice and/or kernicterus. If patients become pregnant whilst taking Sulfonamide, they should contact their doctor for further advice.

Although Sulfonamide can be given to elderly patients, they may be more likely to experience side-effects when taking this medication. Skin and blood problems may be more likely to occur in this demographic so it may be necessary for their dose to be altered if they are prescribed Sulfonamide.

If patients are taking diuretics or water tablets, it can also increase the chance of skin and blood problems occurring. If patients are taking diuretics and notice these side-effects emerging, they should seek medical advice.

Whilst Sulfonamide is regularly used to treat children, it should not be given to babies under the age of 2 months. The presence of side-effects may be greater in infants of this age and adverse effects may occur.


When storing Sulfonamide at home, patients should find a secure location to keep their medication. A closed or locked container, kept at room temperature, should be an appropriate way to store the medication.

Sulfonamide should also be kept out of direct light and away from heat and moisture.

If patients are advised to stop taking the medication or it reaches its use-by date, patients should consult their pharmacist regarding appropriate disposal methods.


Although Sulfonamide derivatives have been used for a long time, they are still highly effective in treating bacterial infections. As well as being used to manage some chronic conditions, such as intestinal disorders, they are routinely used on a short-term basis for the treatment of acute infections.

As most patients are able to tolerate the medication well and Sulfonamide has a high efficacy rate, it's expected that the medication will continue to be used as a treatment for bacterial infections in both children and adults.

Last Reviewed:
December 24, 2017
Last Updated:
April 27, 2018