It is a prescription-only antibiotic for treating certain bacterial infections. It combines two active ingredients — sulfamethoxazole and trimethoprim — in tablet form, and is available in standard and double-strength options. Because it only works against particular bacteria, it’s not right for every infection. Your doctor will decide if it suits your condition and advise the correct dose and duration

What it is and what it is used for

Table of Contents

Active ingredients and class
DUROBAC contains sulfamethoxazole and trimethoprim, two antibiotics used together to treat infections caused by susceptible bacteria.

Indications (uses) — as per the source leaflet
Your doctor may prescribe DUROBAC for bacterial infections such as:

Lung infections (upper and lower respiratory tract).
Urinary tract infections (including bladder infections).
Gastrointestinal tract infections (mouth, gullet/oesophagus, stomach, and intestines).
Genital tract infections, including those that are sexually transmitted.
Skin infections.
Other bacterial infections when the germs are known or expected to be sensitive to this antibiotic combination.

Important: DUROBAC only works against certain bacteria. It won’t help with viruses (like cold or flu) or with infections caused by organisms not sensitive to these antibiotics.

How it works

Speak to your doctor or pharmacist if you would like more information about how this antibiotic combination works.

Who should NOT use this medicine

Do not take DUROBAC if any of the following apply to you:

You are allergic to sulfamethoxazole, trimethoprim, sulfonamides, or any ingredient listed in this leaflet (see “What the medicine contains”).
You have porphyria (a metabolic/haem disorder).
You have severe liver or severe kidney problems.
You have anaemia due to folic acid deficiency.
You are pregnant or breastfeeding.

Warnings and precautions

Before taking DUROBAC, tell your doctor if any of these apply to you or occur during treatment:

Weakened immune system: If you have AIDS or receive treatments that lower immunity (e.g., after an organ transplant), you may be more likely to experience side effects; your doctor may monitor you more closely.
Serious skin reactions: Stop the tablets and get urgent medical advice if you develop a rash (especially with flu-like symptoms), blistering, or peeling skin. Severe reactions have been reported.
Low folic acid: If you have or are at risk of folate deficiency (pale skin, tiredness, shortness of breath), your doctor may prescribe folic acid alongside DUROBAC.
Older adults: You may be more prone to blood problems such as easy bruising or bleeding (thrombocytopenia), especially if you also use certain diuretics (e.g., thiazides).
Kidney problems: Your doctor may need to adjust your dose according to tests. Drink sufficient fluids, particularly at higher doses.
Allergy cross-reactivity: If you are allergic to sulfonamide-containing medicines (e.g., certain diabetes tablets such as gliclazide or glibenclamide, acetazolamide, or thiazide diuretics), you may also react to DUROBAC.
Driving and machinery: It isn’t possible to predict how DUROBAC will affect each person. Do not drive or use machines until you know how it affects you.
Preservative sensitivity: DUROBAC contains Nipastat (parabens), which may cause allergic reactions, possibly delayed.

Note: Always tell your doctor or pharmacist about all medicines and supplements you use, including complementary or traditional products (see “Interactions”).

Pregnancy, planning pregnancy, and breastfeeding

Pregnancy: Safety has not been established. The source states you should not take DUROBAC while pregnant.
Breastfeeding: Safety has not been established. The source states you should not take DUROBAC while breastfeeding.
Planning a pregnancy / unsure: Do not use DUROBAC. Speak to your doctor or pharmacist before use.

Interactions

Tell your healthcare professional about every medicine or supplement you take. DUROBAC may interact with the following (as listed in the source):

Medicines whose effects may increase (monitoring or dose changes may be needed):

Warfarin or other blood thinners.
Methotrexate (used for cancer or immune disorders).
Phenytoin (for epilepsy).
Sulfonylureas for diabetes (gliclazide, glibenclamide, tolbutamide) and repaglinide.
Digoxin or procainamide (for heart rhythm problems).
Lamivudine (for HIV) — high doses of DUROBAC may increase lamivudine’s effects.

Other notable interactions and cautions:

Para-aminobenzoic acid (PABA) supplements: May raise the risk of side effects such as crystals in the urine.
Cyclosporin (e.g., post-transplant): May reduce kidney function further.
Pyrimethamine (for malaria or diarrhoea): May increase the risk of anaemia.
Zidovudine (for HIV): May increase the risk of low blood cells.
Medicines that raise potassium: e.g., spironolactone (a diuretic), steroids (like prednisolone), ACE inhibitors (for blood pressure/heart), and digoxin. These can push potassium to dangerous levels when combined.
Folinic acid supplements: May reduce the effect of DUROBAC.
Hormonal contraceptives: DUROBAC can make contraceptives less effective. Use additional protection while on treatment.
Azathioprine (immune conditions / after transplant): Your doctor may need to monitor your blood counts more often.

Food, drink, and alcohol

Take with food and a full glass of water.
Drink plenty of fluids while using DUROBAC.
No specific alcohol advice is provided in the source.

How to take (Step-by-step)

General guidance

Always take DUROBAC exactly as your doctor prescribes.
Swallow tablets after meals with a glass of water.
Keep well hydrated (drink sufficient water) during treatment.
Finish the full course, even if you feel better earlier, unless your doctor tells you to stop.
If you feel the effect is too strong or too weak, contact your doctor or pharmacist.

Adult and adolescent dosing (12 years and older)

DUROBAC (80 mg trimethoprim + 400 mg sulfamethoxazole):
- Usual dose: 2 tablets every 12 hours after meals.
- Maximum dose: 3 tablets every 12 hours (for particularly severe infections).
- Minimum dose for long-term treatment: 1 tablet every 12 hours.
DUROBAC D/S (160 mg trimethoprim + 800 mg sulfamethoxazole):
- Usual dose: 1 tablet every 12 hours after meals.
- Maximum dose: 1½ tablets every 12 hours (for particularly severe infections).
- Minimum dose for long-term treatment (>14 days): ½ tablet every 12 hours.

Children

The source does not provide dosing information for children under 12 years for these tablet strengths. Your doctor will advise if needed.

Kidney (renal) impairment

Your doctor may order blood tests and calculate an adjusted dose based on the results.
No information is provided in the source for dosing in children with renal failure.

Missed dose

Take the next dose at the usual time. Do not double up to make up for the missed tablet.

Overdose

Taking too much DUROBAC may cause nausea, vomiting, dizziness, or confusion.
Seek medical attention immediately: contact your doctor, pharmacist, the nearest hospital, or a poison control centre.

Practical tips from the source

Take doses regularly every 12 hours to keep levels steady.
Hydration matters: drink plenty of water, especially at higher doses.
With food: helps with swallowing and may reduce stomach upset.

Dosing table (12 years and older)

Formulation	Who	Usual dose (every 12 hours, after meals)	Maximum dose (every 12 hours)	Minimum dose for long-term treatment
DUROBAC (80 mg TMP + 400 mg SMX per tablet)	Adults & ≥12 years	2 tablets	3 tablets (for severe infections)	1 tablet
DUROBAC D/S (160 mg TMP + 800 mg SMX per tablet)	Adults & ≥12 years	1 tablet	1½ tablets (for severe infections)	½ tablet (for >14 days)

Note: TMP = trimethoprim; SMX = sulfamethoxazole.

Possible side effects

Like all medicines, DUROBAC can cause side effects, though not everyone gets them. If your health worsens while taking this medicine, contact your healthcare professional.

Serious — seek urgent medical help and stop DUROBAC

Allergic reactions: swelling of the mouth, tongue, face, or throat, itching.
Severe skin reactions: widespread blistering, peeling, or painful rash, sometimes with fever or flu-like symptoms.
Breathing problems: worsening cough or shortness of breath.
Liver problems: raised liver enzymes on tests; jaundice (yellow skin/eyes), nausea, vomiting, loss of appetite, fever, itching, dark urine, feeling unwell.
Aseptic meningitis: sudden headache or stiff neck with fever.

These reactions can be serious and may require urgent medical treatment or hospital care.

Common

Sulfamethoxazole-related

Thrush/candidiasis (mouth or vaginal fungal infection).
High potassium (may cause palpitations or irregular heartbeat).
Headache, nausea, diarrhoea, rash.

Trimethoprim-related

Headache, itchy skin, rash, fever, nausea, vomiting, sore mouth.

Less common

Pseudomembranous colitis (severe bowel infection causing watery, sometimes bloody diarrhoea).
Blood cell changes (may feel tired, weak, pale, or get frequent infections).
Hypothyroidism (tiredness, weight gain, feeling unusually cold).
Low blood sugar; low sodium; metabolic acidosis (acid build-up).
Decreased appetite.
Mood/neurological effects: depression, hallucinations, psychotic disorder (losing touch with reality), seizures, dizziness, fatigue, insomnia, tingling or numbness in hands/feet, loss of balance or coordination (ataxia).
Eye/ear effects: vision disturbances (e.g., flickering/flashing lights), temporary short-sightedness, eye inflammation with pain/redness, ringing in the ears.
Skin/colour changes: cyanosis (bluish/greyish skin, nails, lips, or around the eyes).
Mouth and gut: vomiting, swollen/inflamed tongue, sore mouth, pancreatitis (severe upper stomach pain with nausea/vomiting).
Sun sensitivity: rash or sunburn-like reaction after sun exposure (even on cloudy days).
Muscle/joint pains: myalgia and arthralgia.
Urinary and kidney problems: difficulty passing urine; passing more or less urine than usual; blood or cloudiness in urine; kidney problems.

What to do: For any troublesome or persistent side effects, notify your doctor or pharmacist. For any of the serious effects above, stop DUROBAC and get urgent medical help.

Side-effect reporting: You can report side effects to SAHPRA using the “6.04 Adverse Drug Reaction reporting form” available on SAHPRA’s website.

Storage and disposal

Keep out of the reach of children.
Store at or below 25 °C in the original container. Protect from light and moisture.
Do not use after the expiry date on the pack.
Return any unused tablets to your pharmacist.
Do not dispose of medicines in drains or the sewerage system (e.g., toilets).

What the medicine contains

Active substances: trimethoprim and sulfamethoxazole.
Other ingredients (excipients): hydrogenated vegetable oil, magnesium stearate, Nipastat (preservative; a mixture of parahydroxybenzoate esters), pregelatinised maize starch, purified water, sodium carboxymethyl starch, maize starch.
Sugar content: Sugar free.

Allergy note: Nipastat (parabens) may cause allergic reactions, which can be delayed.

Pack information and appearance

DUROBAC (standard strength): flat, white, bisected tablets with bevelled edges.
DUROBAC D/S (double strength): white, oblong, biconvex, bisected tablets.

Pack sizes (may vary by market; not all sizes are marketed):

DUROBAC: 28 or 56 tablets in LDPE “ziploc” patient-ready packs; 100, 500, or 1000 tablets in HDPE containers.
DUROBAC D/S: 30 or 100 tablets in white securitainers; 1000 tablets in HDPE containers.

FAQs

1) Can I take DUROBAC if I’m pregnant or breastfeeding?
No. The source states you should not take DUROBAC if you are pregnant or breastfeeding. Speak to your doctor about alternatives.

2) Does DUROBAC affect the pill or other contraceptives?
Yes. DUROBAC can make contraceptives less effective. Use additional protection for the duration of your treatment.

3) How should I take the tablets?
Swallow the tablets after meals with a glass of water. Drink plenty of fluids each day. Take doses every 12 hours as prescribed.

4) What if I miss a dose?
Take your next dose at the usual time. Do not take a double dose to make up for the missed tablet.

5) What should I do in an overdose?
Symptoms may include nausea, vomiting, dizziness, and confusion. Seek medical help immediately: contact your doctor, pharmacist, nearest hospital, or a poison control centre.

6) I have kidney problems — can I still use DUROBAC?
Your doctor may need to adjust the dose after blood tests. For children with renal failure, the source provides no dosing information.

7) Is DUROBAC sugar free?
Yes, DUROBAC is sugar free.

8) Does DUROBAC contain preservatives or common allergens?
Yes. It contains Nipastat (parabens), which may cause allergic reactions, sometimes delayed.

9) Can DUROBAC make me drowsy or affect driving?
It’s not possible to predict individual effects. Do not drive or use machines until you know how DUROBAC affects you.

10) Do I need to finish the whole course?
Yes. It’s important to complete the full course your doctor prescribed, unless your doctor advises otherwise.