Bactrim DS Explained

Bactrim DS is a combination antibiotic that's been used in Australian medicine for decades, and it works a little differently to single-ingredient antibiotics like amoxicillin. If your doctor has prescribed Bactrim DS, here's a general overview of what it treats and how the combination works.

Two Ingredients Working Together

Bactrim DS combines two active ingredients: sulfamethoxazole and trimethoprim. You can find more detail on this combination on the sulfamethoxazole plus trimethoprim ingredient page. Each ingredient blocks a different step in the same bacterial process, specifically the way bacteria produce folate, a compound essential for their growth and multiplication.

By hitting two separate points in the same pathway, the combination tends to be more effective against certain bacteria than either ingredient would be on its own, and it can also make it harder for bacteria to develop resistance to both components at once.

What Bactrim DS Treats

Bactrim DS is used for a range of bacterial infections, including certain urinary tract infections, some respiratory infections, and particular skin and soft tissue infections, among other uses your doctor might consider appropriate for your specific situation. Like all antibiotics, it's only effective against bacterial infections and won't help with viral illnesses.

Why It's Chosen for Certain Infections

Doctors sometimes reach for Bactrim DS specifically because of the particular range of bacteria it's effective against, which can differ from what other commonly used antibiotics like amoxicillin cover well. This makes it a useful alternative, particularly for infections caused by bacteria that don't respond as well to other options, or for people who can't take penicillin-class antibiotics due to allergy.

Things to Discuss With Your Doctor

Bactrim DS contains a sulfonamide component, and people with a known sulfa allergy need to tell their doctor before starting this medicine. It's also important to mention any other medicines you're taking, as sulfamethoxazole and trimethoprim can interact with a number of other drugs, and to let your doctor know about any kidney or blood-related conditions, since these can affect whether Bactrim DS is suitable for you.

Staying well hydrated while taking Bactrim DS is generally recommended, and your doctor or pharmacist will advise you on anything specific to your circumstances, including how it fits with any other medicines you take.

Completing the Course

As with any antibiotic prescribed from the antibiotics category, it's important to complete the full course exactly as prescribed, even if you start feeling better partway through. Stopping early can leave some bacteria alive and better placed to develop resistance, undermining the effectiveness of the treatment and future antibiotics too.

If you notice a rash, unusual bruising, severe stomach upset, or anything that feels seriously wrong while taking Bactrim DS, contact your doctor promptly. Always read the patient information leaflet that comes with your medicine in full, and speak with your doctor or pharmacist about any questions specific to your health and other medications before you start.