What the FDA labels say about taking them together
Penicillin g benzathine and tetracycline
Penicillin g benzathine's FDA label of July 21, 2026 names tetracycline in its drug interactions section; the tetracycline label PlainMeds reads does not name penicillin g benzathine.
Check it at the source: the penicillin g benzathine FDA label on DailyMed (effective July 21, 2026, Pfizer Laboratories Div Pfizer Inc); the tetracycline FDA label on DailyMed (effective March 18, 2025, Heritage Pharmaceuticals Inc. d/b/a Avet Pharmaceuticals Inc.).
What does the penicillin g benzathine label say about tetracycline?
Penicillin g benzathine label, drug interactionsDrug Interactions Tetracycline, a bacteriostatic antibiotic, may antagonize the bactericidal effect of penicillin, and concurrent use of these drugs should be avoided.
Source: FDA drug label (BICILLIN L-A), NDA050141 (King Pharms Llc), as published by Pfizer Laboratories Div Pfizer Inc, effective July 21, 2026 (SPL set 012d46f1-d0a0-4676-a879-cd320297ab16), via openFDA; the full label on DailyMed
What does the tetracycline label say about penicillin g benzathine?
Tetracycline's label (effective March 18, 2025) does not name penicillin g benzathine in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (tetracycline hydrochloride), Heritage Pharmaceuticals Inc. d/b/a Avet Pharmaceuticals Inc., effective March 18, 2025 (SPL set eaa5b1bd-0927-46e4-b941-32fcc492d258), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Penicillin g benzathine | Tetracycline | |
|---|---|---|
| Labeled for | n/a | Bacterial infections |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | n/a | $0.247 per capsule 250 mg capsule |
| Shortage now | In shortage | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once