A Prescription

History Of The 'Prescription'

A prescription, commonly known as an "Rx", has a long and unique history. Early medications were comprised of multiple ingredients that required a trained professional to prepare them. They typically were compounded and manufactured for patient use.

Early on, Latin was adopted as the standard language of the prescription to ensure an understanding between the doctor and the person preparing the medication, also known as a pharmacist.

While Latin is no longer the main language used in prescription writing, many common abbreviations are derived from Latin.

"Rx" is thought to be derived from the Latin word "recipere" which means "take" or "take thus".

Following the symbol "Rx", there are written directions from the physician to the pharmacist on how to prepare medication. "Rx" is also very commonly viewed as an abbreviation for "recipe".

The abbreviation "sig" is Latin for "signatura" and is used on the prescription to indicate the directions for administration.

Modern Prescriptions

The modern prescription has many different components including the superscription, the inscription, and the subscription.

Prescription Example

The superscription includes most of the patient and physician identifying information. It includes the date of the prescription order the name of the patient, the address of the patient, weight, age (although date of birth is the recommended way to write the age).

Many times, the physician information is included in the superscription. The main portion of the prescription, or inscription, contains the name and amount or strength of the drug to be dispensed, or the name and strength of each ingredient to be compounded.

The subscription contains the instruction or directions to the pharmacist and the directions to the patient which is also known as the "sig".  It can either be written out completely or it can be abbreviated. The sig is always transposed onto the prescription label by the pharmacist.

As stated previously, many health care practitioners use Latin abbreviations in their writing of the sig; for example, "1 cap po QAM PRN N/V," means "take one capsule by mouth once every morning as needed for nausea and vomiting.

While using Latin abbreviations for directions is extremely common, it is sometimes frowned upon since they can be easily misinterpreted by both the pharmacist and the patient. Many serious dispensing errors, which at times can be fatal, can be traced to the use of abbreviations.

Who Can Legally Write Prescriptions In The United States?

Doctor Title

There are many different health care professionals that can write prescriptions in the United States. They include:

  • Physicians (MD)
  • Osteopaths (DO)
  • Nurse Practitioners (NP)
  • Physician Assistant (PA)
  • Dentists (DMD) (Limited Prescribing Authority)
  • Certified Nurse Midwife (CNM)
  • Optometrist (Limited Prescribing Authority)
  • Podiatrist (Limited Prescribing Authority)
  • Veterinarians
  • Psychiatrists

Depending on the state of practice, some of these professionals may have limited prescribing authority.

For example, in some states, PA's cannot write for CII controlled substance medications. Another example is a dentist must write a prescription that related to the mouth or a dental procedure.

What Exactly Are Prescription Drugs?

Very simply, prescription drugs are drugs that must be used under the supervision of a physician unlike over the counter or OTC drugs.

They are regulated by the FDA and must go through an intense approval process to be available to the general public.

Controlled Substances

Controlled substance 2

Controlled substances are drugs that have stricter legal prescribing requirements. It is important to note that controlled drugs are classified as such by both the federal and state governments. The governing body with the most strict classification is the law by which you must abide. There are 5 categories of controlled substances:

  • Schedule I
  • Schedule II
  • Schedule III
  • Schedule IV
  • Schedule V

Schedule I (1)

Schedule 1 controlled substances have no accepted medical use in the United States or lack appropriate safety data for use.

Examples of these drugs include heroin and LSD. These drugs are not available to the general public by prescription and medical professionals are not allowed to write for these drugs.

The only time they can be obtained or used is for research purposes by registered individuals.

Schedule II (2)

Schedule 2 controlled substances are available to the public by prescription, but they have very strict prescribing standards.

They have a high potential for abuse and have a high potential for dependence.

Examples of these drugs include Adderall, morphine, and oxycodone. Typically schedule 2 drugs can only be written for one month at a time and cannot be refilled without the issuance of a new prescription.

Schedule III (3)

Schedule 3 controlled substances have a high potential for abuse, although somewhat lower than schedule 2 drugs. Examples of schedule 3 controlled drugs include certain anabolic steroids, hydrocodone (in some states) and ketamine.

Schedule IV (4)

Schedule 4 controlled substances have a potential for abuse and tolerance but less so than schedule 1, 2 or 3 drugs. Examples include Ambien, Provigil, lorazepam, and phenobarbital.

Schedule V (5)

Schedule 5 controlled substances still have abuse potential and that is why they are still classified as controlled drugs. Examples of a drug in this class is Lyrica.

What Are Pregnancy Categories?

In 1979, the FDA developed the pregnancy classification system of United States medications to help health care professionals and patients alike understand the risks of medication use during pregnancy.

  • A: Adequate, well-controlled and generally well-conducted studies in pregnant women have not shown (or have failed to show) increased risk of fetal abnormalities.
  • B: Multiple animal studies have revealed no evidence of harm to the developing fetus. There are however, there are no adequate well-controlled studies in pregnant women.
  • C: Animal studies have shown an adverse effect and there are no adequate and well-controlled studies in pregnant women or no animal studies have been conducted and there are no adequate and well-controlled studies in pregnant women.
  • D: Studies, adequate, well-controlled or observational, in pregnant women have demonstrated a risk to the fetus. However, the benefits of therapy may outweigh the potential risk.
  • X: Studies, adequate, well-controlled or observational, in animals or pregnant women have demonstrated positive evidence of fetal abnormalities. The use of the product is contraindicated in women who are or may become pregnant.


  • Rx, or a 'prescription', is thought to be derived from the Latin word "recipere", or 'recipe'
  • A 'prescription' is required for FDA-approved drugs that must be used under the supervision of a physician.

  • References
    1. The New Pregnancy and Lactation Labeling Rule. AccessFDA
    2. Prescription Requirement Under Section 503A of the Federal Food, Drug, and Cosmetic Act Guidance for Industry. NEJM
    3. Drug Scheduling. PubMed
    4. Comparison of electronic pharmacy prescription records with manually collected medication histories in an emergency department. PubMed
    5. Pharmacist's Letter. Pharmacist's Letter (Subscription Required)