Sulfamethoxazole
Sulfamethoxazole is a sulfonamide antibiotic used together with trimethoprim against urinary, chest, gut and skin infections, sold here as co-trimoxazole tablets in 400/80mg and 800/160mg.
Co-trimoxazole
Sulfamethoxazole, Trimethoprim
400/80/800/160mg
Co-trimoxazole tablets combine sulfamethoxazole with trimethoprim, in 400/80mg and 800/160mg strengths, for urinary tract infections and other bacterial illness.
Why it always comes with trimethoprim
Picture a bacterium trying to divide: it first has to make its own folic acid. Sulfamethoxazole, a sulfonamide antibiotic, blocks one step in that chain, and trimethoprim blocks the next. Our cells never face the problem, since we get folic acid from food. Taken as a pair the two are called co-trimoxazole, and they stop the bacteria multiplying so the body's defences can clear them. Viruses carry no such pathway, so colds and flu do not respond.
What it treats, and how a course runs
Cystitis and other urinary tract infections are what most buyers come for. Co-trimoxazole is also used for travellers' diarrhoea, flare-ups of chronic bronchitis, and skin and soft-tissue infections.
A typical course is a tablet with water in the morning and another in the evening, though some infections call for three or four doses. Food does not change anything. Symptoms often ease by the second or third day; the tablets left in the pack are the ones that finish the job and keep resistance from building, so they get taken anyway.
The strengths sold here
Tablets keep sulfamethoxazole and trimethoprim at a fixed five-to-one ratio. Bactrim and Co-trimoxazole both come as tablets in 400mg with 80mg, and 800mg with 160mg; the higher strength is double the lower one, nothing more than a bigger tablet. Both sit in the shop's antibiotics section, sold in the pack sizes shown on their product pages.
Side effects, and medicines that clash
Stomach upset leads the list: nausea, vomiting, loss of appetite, indigestion. Sulfamethoxazole is known for skin reactions, and that is where attention belongs. A spreading rash, or skin that blisters or peels, needs urgent treatment, as do fever or chills, a sore throat, bruising or bleeding you cannot explain, yellowing of the eyes or skin, and shortness of breath. Diarrhoea that turns watery or bloody can start during the course or up to two months after the last tablet. Sun burns more easily, so cover up and use sunscreen. Blood thinners such as warfarin can become too strong on co-trimoxazole, and some blood-sugar-lowering tablets are affected; taken with ACE inhibitors or potassium-sparing water tablets, potassium can rise too high. Phenytoin and methotrexate are also affected.
Sources
- Co-trimoxazole: MedlinePlus Drug Information — MedlinePlus
- Co-Trimoxazole 160mg/800mg Forte Tablets - Summary of Product Characteristics (SmPC) - (emc) — electronic medicines compendium (emc)
Is Sulfamethoxazole available to order in Hong Kong?
Sulfamethoxazole can be ordered online with delivery to Hong Kong, combined with trimethoprim as generic Bactrim or Co-trimoxazole tablets, both in 400/80mg and 800/160mg. Payment can be made by Visa, Mastercard or American Express on a secure encrypted page, or with Bitcoin or Ethereum.
What is the price of Sulfamethoxazole?
Each of the two sulfamethoxazole products has its own price per pack, shown on its page in HKD or your chosen currency; larger packs usually cost less per tablet.
Do I need a prescription to order Sulfamethoxazole?
PockDose does not ask you to upload a prescription when you order sulfamethoxazole. See the ordering FAQ for details.
What is another name for sulfamethoxazole and trimethoprim?
Bactrim is a brand name of sulfamethoxazole and trimethoprim, which are also sold as Septra and Septrin. Here, sulfamethoxazole and trimethoprim can be bought online as generic Bactrim and co-trimoxazole tablets. These are generics, not the original brand.
What is the difference between sulfamethoxazole and co-trimoxazole?
Sulfamethoxazole is one antibiotic; co-trimoxazole is the name for that antibiotic combined with trimethoprim. The two are almost never used apart, because blocking neighbouring steps of the same bacterial pathway works better than blocking only one of them.
What does 400/80mg mean on a co-trimoxazole tablet?
Read it as sulfamethoxazole first, trimethoprim second: one tablet carries 400mg of the first and 80mg of the second, a five-to-one ratio. Step up to 800/160mg and both amounts double, so the proportions never change.
How quickly does co-trimoxazole start to work?
Expect a first change within a couple of days. Burning when you pass urine tends to ease before the need to go so often does, and a good start is not proof the infection has gone.
Does co-trimoxazole make the contraceptive pill less reliable?
No. Only rifampicin and rifabutin, antibiotics used mainly for tuberculosis and a few other infections, lower the reliability of the pill, patch and ring. Co-trimoxazole is not one of them. Vomiting or severe diarrhoea during a course can still affect how well a pill is absorbed.