Prescribed medicines in England reached the milestone in 2012. It marks a rise of 62% compared with a decade before.
Health and Social Care Information Centre (HSCIC) figures show net costs stood at £8.5bn in 2012, a fall for the second year running.
The NHS dispensed 18.7 items per person on average in 2012, up from 12.4 in 2002. Net cost per item has fallen from £11.10 in 2002 to £8.50 in 2012.
The ageing population is driving the rise in prescriptions, while costs are falling as more drug patents expire and generics become available.
For example, the net cost of atorvastatin fell by £144m between 2011 and 2012, from £311m to £167m.
Diabetes prescriptions accounted for the biggest cost by treatment area for the sixth year running at £768m, a 2.2 per cent (£16m) rise on 2011.
Antibiotic costs leapt 15% to £196m, while items prescribed rose 6% to 43m.
Nine out of 10 prescribed medicines were dispensed free of charge.
HSCIC chair Kingsley Manning said: 'For the first time, one billion prescription medicines have been dispensed to our communities in just one year. This figure reflects a continuing upward trend in prescription numbers, which is in contrast to a recent fall in total net cost.
'Total costs have fallen for the second year running and are now at 2009 levels. Our report shows that while people on average now receive more prescription items, the cost of these per head has dropped in the last two years.'