Is a half dose of 5mg exactly the same as full dose of 2.5mg?!

[AmberPanda]

Sorry if this is a stupid question but I was quite happy on 2.5mg so ordered a second 2.5mg, but the suppression started to wear off. Next I ordered a 5mg pen and had one dose of about 3.75mg and had terrible side effects. I have since dropped down to half dose so should be back on 2.5mg but I’m still having v bad side effects and also a real reaction on my injection site which I never had with my 2.5mg pen. It’s so itchy and raised!

I wondered if the higher concentrate in a small amount of liquid made it more intense?

There's no stupid questions here! But yes, half a 5mg dose is the same as one 2.5mg dose. Think of it like cutting a 500mg paracetamol pill in half.
Your side effects may just be a result of the med building up in your system as it's got a 5day half life so when you take your 2nd dose after a week, you've still got some of the 1st dose in your body. I advise speaking to your prescriber for more advice.

Ah ok that makes sense! I’ve just given myself a bit of a longer break as last week almost threw out the pen in the middle of the night as felt so sick and vowed never to put it in my body again! But going to try again as I’m so close to goal weight but still need the help!

Yes I've seen it advised to spread out doses to 8 or 9 days if SEs are bad, as this lowers the total amount in your system. Bear in mind, that some people just simply can't tolerate some meds so don't persevere if it's not getting better. Re the skin reaction - I had this when I injected in my belly after about 2 months (the skin there is quite thin and sensitive) so moved to the thigh and no problems since. You can also take an antihistamine or use insect bite cream to take away the itchiness.

I really, REALLY struggled with the step up
to 5mg and ended up dropping to 4 then up
to 5 again. It took me about 3 months to go up to 7.5mg but, honestly that jump has been plain sailing (3rd dose at that level this morning).

For the itchiness, mine started around week 8, I have had some success changing from a 4mm to 6mm needle on the advice of my provider, it is still a bit red, but not itchy and goes away quicker.

I have 8mm ordered with my next pen to try. 4mm - 8mm (and I think, but check for sure if considering, even 12mm although that is too scary for me!) are all subcutaneous lengths of needle, the slightly longer needle takes the injection further away from the sensitive skin area into the less reactive subcutaneous fat layer. Although be warned some also say that they think the injection is more effective too with a longer needle - I think I have felt this, but know it might just be my imagination!

For the dose I would not advise extending to taking every 8-9 days. The half life of the medication is suited to 7 days. Extending it further will give you the lower spikes so less side effects, but also lower dips. I would stay at 7 days, and either stick with 2.5mg and see if it improves or if you'd rather reduce the risk drop further down to 1.75mg-2.0mg for a week and see how you go.

Good luck!

Yes, 5 ÷ 2 = 2.5.

It can't be anything else.

But you can't use a 5mg pen (or any pen) for longer than 30 days, so don't try to stretch it out to 8 doses.

Well... it could be 'something else' if the concentration is different. My knowledge in this area is extremely theoretical but the drug companies have to put a lot of work into their formulations, peptide/protein therapeutics can be affected by concentration in various ways.

Most likely it's the half life as PP have suggested but sometimes things can be a bit more complicated in ways that may not be at all obvious!

Well... it could be 'something else' if the concentration is different.

No it can't.
It's simple maths.

2.5mg in 0.3ml vs 2.5ml in 0.6ml might absorb differently.

From what I read smaller volumes/higher concentrations might be absorbed quicker or might cause more irritation but, for subcutaneous injections the difference will be minimal for most and if you were moving to 5mg any way you would get an injection reaction with way.

Not sure if I would try (for example) 2.5mg from a 15mg pen as the tiny amount of liquid you would use would be difficult to measure with wastage in the needle, but between a 2.5mg and 5mg pen the effects are likely to be very similar/identical.

I appreciate that you're not supposed to use a pen beyond 30 days, but I know I'm not alone in stretching it beyond that for smaller doses. I used my last pen over 30 days (I had awful side effects on my first dose of 5mg, so dropped back down and built up again slowly) and have been absolutely fine.

yes this was where my musings came from - I’m injecting half the amount of liquid from a 5mg but with the same strength as a full dose of 2.5 so it is more concentrated. It’s not the same as cutting a pill in 2 as such.
it’s like taking either 2 spoons of weak medicine or one spoon of stronger medicine?
but yes I think it’s more the build up in my system. Urgh I was so smug how well it was working with so few side effects, I guess it was a bit too good to be true!

Did the longer works? I have really bad injection site reactions and nothing works

The 6mm wasn't as itchy as the 4mm but still red, but I chickened out of the 8mm (too long 🤣). These were all BD Viva needles.

I then remembered it started when I changed supplier so I tried some 6mm spare needles I had from my previous supplier (Novofine) and I haven't had a reaction since (bought a box). For me I think I must have been reacting to a coating or something different about the BD Viva needles.

I have heard others find taking it out of the fridge for 30 minutes helps them.

@WeAllHaveWings i have tried two different brands but may try longer needles
thanks