Medicines and prescriptions
BID, TID, QID and QD: What They Mean on a Prescription
BID, TID and QID · say it: bee-eye-DEE, tee-eye-DEE, kew-eye-DEEAlso written: b.i.d., t.i.d., q.i.d., QD, twice daily
Short answer
BID, TID and QID are abbreviations on prescriptions meaning twice a day, three times a day and four times a day.
What it means
These abbreviations come from Latin phrases: bis in die (twice a day), ter in die (three times a day) and quater in die (four times a day). They tell you how many times a day a medicine is meant to be taken.
Side by side: QD or OD means once a day, BID twice a day, TID three times a day and QID four times a day. So the difference between BID and TID is one extra dose in the day. Doses are often spread across waking hours, for example morning and evening for BID, or morning, midday and evening for TID, but the right spacing depends on the medicine.
You may also see OD or QD (once a day), Q6H or Q8H (every 6 or 8 hours), AC (before meals), PC (after meals) and HS (at bedtime). Some hospitals discourage these abbreviations because they can be misread, so many labels now spell instructions out in full. The abbreviation tells you frequency, not the exact times. If you are unsure how to space doses or whether to take them with food, a pharmacist can explain.
Where you may see it
- Prescriptions and medicine labels
- Hospital medication charts
- Discharge summaries
📄 How it looks on a report
Amoxicillin 500 mg PO TID x 7 days
🙅 What it does not mean
- Three times a day does not always mean exactly every eight hours; ask whether timing matters for your medicine.
- BID is not the same as "every 12 hours" in every case, although it is often spaced that way.
- The abbreviation does not tell you the dose; that is written separately on the prescription.
🗒️ Questions to ask your doctor
🧾 Reports where you will see “BID, TID and QID”
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💊 Medicines whose labels mention “BID, TID and QID”
Plain-English explanations of each medicine, from its official FDA label.
- Atorvastatin
a statin, a cholesterol-lowering medicine of the HMG-CoA reductase inhibitor type
- Escitalopram
a selective serotonin reuptake inhibitor (SSRI), a type of antidepressant
- Famotidine
A histamine-2 (H2) receptor blocker, a type of medicine that lowers stomach acid.
- Pantoprazole
a proton pump inhibitor (PPI), a medicine that reduces the amount of acid the stomach makes
- Rivaroxaban
a factor Xa inhibitor, a type of blood thinner (anticoagulant)
🔗 Read more from trusted sources
- “BID, TID and QID” on MedlinePlus ↗
US National Library of Medicine
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