Sulfamethoxazole 400 mg / trimethoprim 80 mg is the standard-strength oral tablet presentation of the fixed TMP-SMX antibiotic combination. The same ingredient amounts are associated with regular branded Bactrim tablets and generic products listed under their nonproprietary names. A generic search result might display the amounts in reverse ingredient order, so both names must be checked.
The 400/80 mg label identifies a product, not a suggested dose or treatment schedule. It also must not be confused with the oral suspension labeled 200/40 mg per 5 mL or with the double-strength 800/160 mg tablet. Strength and dosage form are separate parts of the pharmacy order.
This guide is organized around the standard-strength ingredient-defined tablet across generic suppliers. For the trade-name product, see regular branded Bactrim tablets; the alternative strength is described in the 800/160 mg generic tablet guide.
A listed tablet should identify sulfamethoxazole 400 mg together with trimethoprim 80 mg. Neither component alone represents Bactrim. When browsing a pharmacy catalog, confirm the complete combination field and avoid selecting items based only on an abbreviated search term.
Regular or single-strength refers to the per-tablet amount compared with the common DS presentation. The ratio between the two components remains 5:1. “Regular” does not imply over-the-counter availability or lower medical risk; it is simply the marketed tablet designation.
Approved generic listings can have different labelers, imprint characteristics or package sizes. Equivalence and substitutability are regulatory and professional determinations, not a consequence of matching a few words on the label. Consult FDA approval information and the licensed dispensing pharmacist.
For U.S. listings, distinguish the firm shown as labeler from any repackager and from the manufacturer identified in supporting records. A different imprint or package NDC can prompt a patient question without implying a different approved active ingredient. If the proposed generic is unclear, ask the pharmacist to confirm the actual product and its applicable equivalence status rather than relying on a web-catalog title.
Match the tablet strength to both active ingredients before considering labeler, package quantity or pharmacy payment. A standard-strength item must show sulfamethoxazole 400 mg and trimethoprim 80 mg per tablet; the “regular” description alone is insufficient if a search result mixes tablets with liquids. This checklist is deliberately focused on generic identification, whereas the separate regular Bactrim brand page addresses the proprietary product name.
| Element | Expected 400/80 mg identity | Frequent mix-up |
|---|---|---|
| First component | Sulfamethoxazole 400 mg | 800 mg DS amount |
| Second component | Trimethoprim 80 mg | 160 mg DS amount |
| Combination | Both ingredients in one tablet | Single-agent trimethoprim |
| Route | Oral tablet | Oral suspension |
| Product status | Specific approved marketed item | Treating an NDC as an approval certificate |
The liquid combines ingredients per 5 mL, not per tablet. Switching involves prescribed dosage form, concentration, patient circumstances and pharmacy preparation. The TMP-SMX suspension guide covers liquid identity and measuring-device checks without giving conversion instructions.
Ask for the complete drug name, both ingredient amounts, dosage form, package quantity and printed directions. If the pharmacist detects a conflict between the e-prescription and selected product, clarification with the prescriber is preferable to inferring intent.
A useful record includes the package NDC, the full ingredient statement, oral-tablet designation and the quantity actually dispensed. If the bottle lists the two ingredients in reversed name order, check which milligram amount belongs to each chemical name. A matching total number of milligrams alone cannot establish that the correct combination product was supplied.
A lower amount per tablet does not predict a lower total payment for a prescribed course. Quantity, pharmacy contract and payer terms can influence pricing. Compare the authorized fill with its appropriate alternatives only; the overall Bactrim pricing methodology explains the financial variables.
Even with a familiar generic label, the medicine can cause severe hypersensitivity and interact with other prescriptions. Kidney function, pregnancy, age and potassium risk can change whether the clinician prescribes it. Product identification is only one stage in a safe dispensing process.
400 mg sulfamethoxazole and 80 mg trimethoprim.
No. Bactrim DS contains 800/160 mg per tablet.
Yes, it is the common standard-strength oral tablet presentation.
FDA-approved generic TMP-SMX tablet products use that ingredient combination and strength.
No. Directions depend on the clinician’s prescription.
Not on your own. A change must be clinically authorized and verified by a pharmacist.
Not reliably across all suppliers. Verify imprint, ingredient label and pharmacy record.