Abbreviations on a doctor's letter

[WashAsDelicates]

Continue long acting p.r.n. antihistamines, eg BD or TDS

What do p.r.n., BD and TDS mean?

Thanks.

prn - when needed
bd - twice a day
tds - three times a day

Prn = as and when needed

Bd= twice daily

Tds = three times daily

All from the Latin i believe.

Sorry - which means 'take antihistamines as you need them, whether that's two or three times a day and not if you don't'.

PRN - as required
BD - twice a day
TDS - three times a day

p.r.n is “as required”. BD is twice a day. TDS is three times a day.

prn as/when required. BD twice a day TDS threetimes a day

prn comes from the Latin 'pro re nata' which translates as 'when the circumstances arise' - hence as and when needed

BD is from "bis in die" (Latin for 'twice in a day')

TDS is "ter die sumendum" ('to be consumed three times a day')

Thanks.

Particularly for the Latin lesson 😄