The Oral Syringe: The $0.15 Device That Ended the Teaspoon's 150-Year Medical Career
For most of the 19th and 20th centuries, the teaspoon was a medical dosing device. Apothecaries compounded medicines and labeled them in teaspoon and tablespoon doses. The assumption was that every household had a teaspoon and that every household's teaspoon was roughly the same size. The assumption held, barely, when the alternative was a graduated glass dropper that cost more than the medicine itself. The oral syringe —a plastic barrel with a rubber plunger, graduated in 0.1 mL or 0.01 mL increments —was invented in the 1950s, became common in hospitals in the 1970s, and was included in OTC children's medicine packages by the 1990s. A 2016 national survey found that 85% of US parents who gave their children liquid medication used the dosing device provided in the box. The remaining 15% used a kitchen spoon. The 15% accounted for the majority of pediatric dosing errors. The oral syringe won the war against the teaspoon —not by outlawing the spoon but by making the syringe so cheap and ubiquitous that using a spoon became the exception rather than the default. The conversion from mL to teaspoons is still printed on the label. The syringe makes the conversion unnecessary.
Standard Pediatric Doses: The mL-to-tsp Table That Lives on Every Pharmacy Printout
| mL dose | US tsp equivalent | Typical medication and patient |
|---|---|---|
| 0.5 mL | 0.101 tsp | Infant vitamin D drops (newborn). One-tenth of a teaspoon —impossible to measure with a spoon. |
| 1.25 mL | 0.254 tsp | Infant acetaminophen (6—1 months). One-quarter teaspoon. Use the syringe. |
| 2.5 mL | 0.507 tsp | Children's ibuprofen (12—3 months). Half a teaspoon. The syringe has a 2.5 mL line. |
| 3.75 mL | 0.761 tsp | Children's acetaminophen (2— years). Three-quarters of a teaspoon —the most error-prone fractional dose. |
| 5 mL | 1.014 tsp | Children's antibiotics (4— years). "One teaspoon" —the standard pediatric unit. The dose every parent has measured. |
| 7.5 mL | 1.522 tsp | Children's acetaminophen (6— years). 1.5 teaspoons. The dose that requires either a 5 mL + 2.5 mL draw or a graduated cup. |
| 10 mL | 2.029 tsp | Adult cough syrup (half-dose). Two teaspoons. The medicine cup's 10 mL line. |
| 15 mL | 3.043 tsp | Adult NyQuil / DayQuil. Three teaspoons = 1 tablespoon. The standard adult liquid dose. |
tsp (US) = mL × 0.202884136 | tsp (metric) = mL ÷ 5
The Coffee Spoon, the Iced-Tea Spoon, and Other Flatware That Is Not a Teaspoon
A demitasse spoon (espresso spoon) holds 2.5—.5 mL —about half a US teaspoon. An iced-tea spoon (the long-handled spoon served with iced tea in the American South) holds 6— mL —about 1.3 US teaspoons. A Chinese soup spoon (the ceramic ladle-shaped spoon) holds 15—0 mL —an entire tablespoon. A Korean rice spoon holds 8—0 mL. The word "teaspoon" in English refers to a specific small spoon designed for stirring tea, with a bowl capacity of roughly 5 mL. But the flatware drawer contains a dozen spoons called by other names, each with a different capacity, and at 3 AM with a sick child, the distinction between a teaspoon and a demitasse spoon is invisible in the dark. The oral syringe, with its large-print mL markings and its physical immunity to silverware drawer confusion, solves the problem not by educating the user about teaspoon taxonomy but by making the spoon irrelevant. For more on the spoon taxonomy and the US-vs-metric teaspoon definition gap, see teaspoons to mL. For the tablespoon-level dosing problem, see mL to tablespoons.
Frequently Asked Questions
Can I use the "1 tsp = 5 mL" rule for baking?
Yes. The 1.4% difference between a US teaspoon (4.93 mL) and a metric teaspoon (5 mL) is smaller than the manufacturing tolerance of most measuring spoons (±5% for mass-market stainless steel spoons). A recipe calling for 1 teaspoon of salt measured with a US spoon (4.93 mL) vs a metric spoon (5 mL) differs by about 0.07 mL —roughly the volume of one grain of rice. The human tongue cannot detect the difference in a finished dish. The only caveat: if the recipe is a European pastry that was developed with metric teaspoons (5 mL) and lists all its measurements in grams except for a few critical small-volume ingredients (baking powder, salt, spices), the 1.4% error in those small-volume ingredients is unlikely to ruin the pastry. For bread and pastry where precision matters, use grams —a scale is the device that makes the US-vs-metric teaspoon distinction moot. For more on scale-vs-spoon precision: cups to mL and the Volume Guide.
How many mL is "a dash" or "a pinch"?
These terms have no legal definition but follow loose conventions: a dash = 1/8 tsp ≈0.62 mL (US). A pinch = 1/16 tsp ≈0.31 mL (US). A smidgen = 1/32 tsp ≈0.15 mL (US). Measuring spoon sets that include these labels (sold as "mini measuring spoon sets" on Amazon) are novelties —no recipe author writing before 1990 expected a cook to own a "smidgen" spoon. A dash meant "tip the spice jar and give it one quick shake." A pinch meant "pick up as much as you can between your thumb and forefinger." The volume varies by the size of the shaker holes, the moisture content of the spice, and the dimensions of the cook's fingers. Recipes that specify dashes and pinches are not written for precision bakers. They are written for cooks who taste as they go and adjust by feel. The mL equivalents are approximate. For actual measuring, use a set that starts at 1/4 tsp. Below that, the human hand is the measuring instrument, and the scale's resolution is the limiting factor rather than the spoon. For more on fractional spoons and their uses, see teaspoons to mL.
Engineering Context
1 mL = 0.202884136 US teaspoon —the reciprocal of 4.92892159 mL/tsp. The conversion is exact but is almost never used in regulated manufacturing because the teaspoon is not a legal unit of measure for pharmaceutical products in the US (21 CFR 201), the EU (EMA guidance), or any WHO-member pharmacopeia. The oral syringe graduated in mL is the standard-of-care dosing device. The US teaspoon survives in the label's parenthetical and in the cultural habit of translating mL into "about a teaspoon." That translation is not an engineering problem —it's a human-factors problem. The conversion from mL to teaspoons is mathematically sound and physically unreliable, because the object called "a teaspoon" is not calibrated. The correct engineering response is to remove the teaspoon from the process: design the dosing device, print the label in mL, and let the conversion exist only as an informational courtesy for users who do not yet trust milliliters. For related pages: tsp to mL, tbsp to mL, mL to tbsp, mL to cups, and the Volume & Cooking Guide.