"I'll double up tomorrow"

Here the leaflet earns its keep, because the NHS advice on missed doses is short and it's the same across most of the medicines in this book.

If you forget a dose, check the leaflet. If you're not sure, ask a pharmacist or a GP. In most cases you take the missed dose as soon as you remember and carry on as normal, but if it's nearly time for the next dose, you skip the one you missed and take the next one at the usual time. And then the line that's on the antibiotics page, the levothyroxine page and most of the others. Do not take a double dose to make up for a missed one.

The reason people double up is that it feels like repairing the mistake. The tablet was owed, so pay it back. But the body isn't a ledger. Two doses close together mean a higher level of the drug than the prescriber intended, and the NHS antibiotics page says the risk of side effects goes up when doses are taken closer together than recommended. For most medicines one accidental extra dose is unlikely to do serious harm, and the pages say so. For some it matters more, and the leaflet will say. The rule is the same for all of them. Missed is missed. Move on to the next one.

This is also where the fade does its quiet damage, because a person taking a tablet when they remember is making this decision several times a week without knowing they're making it. Was it this morning or yesterday. Take one now and one tonight to catch up. The reader who has a hook, in chapter 21's sense, rarely has to think about a missed dose, because a missed dose becomes visible. There's a compartment still full. And when there is one, the answer is already written down in the box.