Many dermatologists believe in a cumulative dose when prescribing Roaccutane (recommended by the BNF.org guidelines).
The idea is that the patient must take a certain amount of Istotretinoin to avoid relapsing in the future.
If the patient has a relapse (acne returns) a second course may be recommended at least 8 weeks, after their first course has ended.
For children and adults over 12 years old, Roaccutane dosage can range from 500 micrograms/kg to 150 mg/kg per 2.2 pounds of body weight. This is usually divided into two doses for 14 to 24 weeks.
For the sake of this post we will say that the cumulative dose is 120 mg (which seems to be a popular dose on this site).
The cumulative dose is worked out by multiplying your body weight in kg by 120mg. An example of how the cumulative dose could be worked out is shown below:
I weigh about 57kg, so the dermatologists has worked with the figure 60kg as a rounded up figure. Thus: 60kg X 120mg = 7,200mg cumulative dose of Roaccutane.
At 60mg per day (my maximum recommended dose for my weight), the Dermatologist then calculates how many days are required to reach this target dose:
7,200mg divided by 60mg = 120 days (i.e. about 4 months).
Please note: these figures will vary depending on the weight of patient, height of patient, dermatologist’s professional opinion and severity of the patient’s acne.
Rachael_M
2nd Apr, 09
What happens if you go over your cumulative dose? Does it not matter or can it be harmful? My dermatologist is planning to keep me on Roaccutane for another 2 months, but that would mean about 2 weeks over my c.dose…
atRach
Will
2nd Apr, 09
Hi Rachael, I’m no professional but I don’t think it matters. In my opinion, a cumulative dose is a rough guide that derms follow and shouldn’t be viewed as the precise dose needed to cure your acne. Also, 2 weeks isn’t a lot – view it as two weeks more chance of beating acne, rather than 2 weeks extra of potential harm. :)
atLouise
28th Apr, 09
Sorry to seem like a complete idiot – I still don’t get it.
I weigh about 57kg too but not sure where the 120mg comes from?
I was on 20mg a day for 42 days and am now taking 40mg a day.
All I want to know is when I will be off the tablets, I don’t see my dermatologist as often as everyone else it seems but she was very happy with me the last time I went and am booked to see her in June.
Thanks
Louise
atsparklypickle
28th Apr, 09
I think this means a total of 120mg of Roacc per kg of body weight is typically taken during a sucessful course.
atWill
1st May, 09
Hi Louise, Sparklypickle is correct – 120 mg is perceived by some dermatologists as the minimum cumulative dosage (per kg of body weight) required to avoid acne returning once you have finished your roaccutane course.
60 kg x 120 mg = 7200 mg (your target cumulative dose of roacc)
If you were on 20 mg a day for 42 days that means that you’ve already had 840 mg of roacc (20 x 42 = 840)
So you have 6360 mg to take (7200 – 840 = 6360)
6360 mg divided by 40 mg (your current daily dose) = 159 days
These is just a rough guide and figures can vary depending on the weight, height and your derm’s opinion.
atBelinda
19th Jul, 09
When I first went on Roaccutane, my dermatologist worked out a formula which was a higher dose initially and gradually became a lower dose. She also made it compulsory for me to take a contraceptive pill while on roaccutane. And, yes I agree it depends on a case to case basis. Remember one 60kg person could have more severe acne than the next 60kg person. Surely that is also taken into consideration. I would rather take the higher end of the normal dose than a lower dose; otherwise you end up like me, who now 10 years later needs to go on roaccutane again. I have been on Diane 35 for many years to control acne (even after being on Roaccutane), which can’t be good for your system, feeding it all that progesterone and whatever else it contains. No more – I want another potent dose of roaccutane to cure it (acne) once and for all… God bless the inventors of Roaccutane.
athaley
18th Sep, 09
hi, i have been on roaccutane for 2 months now and they have not done one good thing for my skin!
atmaybe i am taking too small of a dose – i take 30mg per day, i am 10 stone and 5ft10”…
should i take a higher dose?
SR
1st Nov, 09
this explains to me why why first dose of roacc didnt work.
i weigh 60kg and was put on 20mg per day for 6months.
it either should have been 60mg per day for 4 months, or 20mg for 12 months!! thats mad! no wonder its come back!!
atazza
21st Jan, 10
ive been on 2 a day with doses varifying from 2 – 1 but when i go down the dose i get my spots come back again badly, Should i still be aloud on them? is there a limited time your aloud to be on them?
at