Understanding Your Prescription: Dosage, Generics, and Drug Interactions

Learn how to read prescriptions: dosage instructions, treatment duration, generic medications, and what you need to know about drug interactions.

A prescription can sometimes look like an encrypted document with its abbreviations and complex instructions. This guide helps you understand what your doctor has prescribed.

Important

Never modify your treatment without medical advice. If in doubt about your prescription, consult your pharmacist or doctor.

Anatomy of a Prescription

A valid prescription must contain several required elements:

Prescriber identification

Name, credentials, address, license number, signature

Patient identification

Name, date of birth, sometimes weight for children

Prescription date

Essential for validity (varies by medication type)

Medications prescribed

Drug name (generic or brand), dosage, form, instructions, duration, quantity

Understanding Dosage

Dosage indicates how to take your medication.

Common Abbreviations

Abbreviation	Meaning
tab	tablet
cap	capsule
mg	milligram
g	gram
mL	milliliter
IU	International Unit

Timing of Doses

🌅

Morning

☀️

Noon

🌆

Evening

🌙

Bedtime

Common Expressions

QD = once daily
BID = twice daily
TID = three times daily
PRN = as needed
AC = before meals
PC = after meals
HS = at bedtime

Why Timing Matters

Absorption depends on context

Empty stomach: faster absorption, stronger effect
With food: better digestive tolerance
At night: some medications work better (statins, blood pressure meds)

Generic vs Brand Name

What is a Generic Drug?

A generic drug contains the same active ingredient as the brand-name drug, in the same dose and form.

Example: Acetaminophen (generic) = Tylenol (brand name)

Generic Medications

Criteria	Brand Name	Generic
Active ingredient	Identical	Identical
Dose	Same dose	Same dose
Effectiveness	Comparable	Comparable (bioequivalence required)
Inactive ingredients	Specific	May differ
Price	Higher	Usually lower

Generics have the same effectiveness as brand-name medications. They must prove bioequivalence to be approved.

Why 'Dispense As Written'?

If your doctor writes "DAW" (Dispense As Written), the pharmacist cannot substitute a generic. This is rare and usually justified (allergy to an inactive ingredient, narrow therapeutic index).

Drug Interactions

Watch for combinations

Some medications don't mix well. Always inform your doctor and pharmacist of ALL medications you take, including over-the-counter drugs and supplements.

Common Interactions to Know

Important Interaction Examples

Blood thinners + Aspirin: increased bleeding risk
Some antibiotics + Birth control: possible reduced effectiveness
Statins + Grapefruit: increased muscle toxicity
NSAIDs + Lithium: lithium overdose risk
Antidepressants + St. John's Wort: serotonin syndrome

Alcohol and Medications

⚠️

Sleep aids

⚠️

Anxiety meds

⚠️

Antihistamines

⚠️

Pain medications

Important

Alcohol amplifies the sedative effects of many medications and can cause dangerous drowsiness, especially when driving.

Prescription Validity and Refills

Duration of Validity

Prescription Type	Validity
Standard prescription	Varies by state/country
Controlled substances	Stricter limits apply
Contraceptives	Usually up to 1 year

Refills

Short-term treatment

No refills planned. Consult if symptoms persist.

Chronic treatment

Often refillable (note indicates number of refills)

Expired prescription?

The pharmacist may provide an emergency supply for chronic medications, but see your doctor soon.

Special Notes

Medications Requiring Extra Caution

Warning Labels

Drowsiness warning: Avoid driving
Pregnancy warning: Not safe during pregnancy
Take with food: Reduces stomach upset

Practical Tips

Keep your prescriptions

Save them for at least 1 year for reference and insurance.

Ask questions

Don't hesitate to ask the pharmacist to explain dosage.

Use a pill organizer

For complex treatments, a pill organizer prevents missed doses and confusion.

Centralize your data

With Genki, keep a history of all your treatments.

How to Use Genki for Your Prescriptions

With Genki, you can:

Scan your prescriptions and import them automatically
Extract medications with their dosages
Keep a history of all your treatments
Ask questions to the AI about your medications

Useful feature

When seeing a new doctor, you can show them your complete treatment history stored in Genki.

"
If you suspect an adverse effect, contact your doctor. You can also report side effects through official channels in your country.
"

— Safety reminder