In the good old days I took over-the-counter medication for backaches. My pain was bad, so I took extra-strength tablets. The “extra” on the label meant that each tablet contained twice as much painkiller as the regular-strength ones.
In the good old days I took an over-the-counter decongestant to defuse migraines. I took regular-strength decongestant tablets rather than the extra-strength ones. The “extra” on the label meant that each tablet included a painkiller: Its dose of decongestant was the same as the regular-strength tablets. Because my migraines didn’t always present with pain, I medicated the pain independently.
That was the good old days when “extra” meant, well, “something more”: more of the same painkiller in one case, more medicinal ingredients in the other.
Today, the Big Guy went to buy more over-the-counter cold medication, because I had gone through our stock of extra-strength caplets and still felt crummy. He returned with regular strength, that being all they had in stock. I looked at the two labels to see how they differed.
They do not differ: Each caplet contains the same ingredients, in the same amounts.
So, what makes one box “extra-strength”? The dosage. To achieve an extra-strength effect, take two regular-strength caplets, conveniently contained within.
Ah for the good old days, when “extra” actually meant “something more.” Something more than “take two.”