Endometriosis UK
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Zoladex - 28 day strict rule?

I have given in and am finally getting the monthly zoladex injection/ implant next week.

I have been reading that the implant needs to be administered every 28 days. Can anyone advice if this is a strict rule?

I have worked out I will be in holiday when my 3rd injection is due.

I could get it done just before I go which would be day 24.

Or do I need to wait until I am back from holiday (day 37) - could I start bleeding whilst on holiday?


9 Replies

Hi Sarah,

Hope you are well.

I had my third injection last Tuesday and was asking my GP this question ...

She said if I was to go over the 28 days I could potentially have a bleed - which would then fail the whole idea of the Zoladex I feel.

I ask how about having it early... she said that potentially could have more side effects / worst side effects. (Eg hot flushes)

Hope that helps - hear to talk if you want :)

Rachel xx


Thanks Rachel.

Wow it’s so restrictive! Really not looking forward to it. I might actually postpone the date of my first injection to time it around my holiday.

How have you been getting on with it?



No worries Sarah ..

Yeah I am trying to think about my September holiday and injections:/

Are you heading anywhere nice?

Not too bad.. I think some people have the side effects pretty badly.

Some of the side effects I have had so far-

Hot flushes

Headache/migraines (but that was only for a few days luckily as they were not nice)

Memory fuzzy

Joint achy (but I have been taking an extra calcium vitamin to help with joints)

How long have you got to have the injections for?



They want me to try for 4 months at first and see how I get on.

I had surgery about 2 months ago which was partly successful - the endo that is left is in places where there is a high chance of bowel damage or utera damage so this zoladex is to try and avoid another op. I hope it’s the side effects aren’t too bad!

Off to portugal - really looking forward to it but now worried I will be having hot flushes / not feeling myself.

Thanks for the info and it sounds like you are getting on well with it.

Have you had any bleeding since you started it?


I see - so have they said will they do a scan to see how the endometriosis is? (Eg to avoid another surgery)

Ooh Portugal -lovely! Have you been there before?

As it would be your third that potentially you could have early .. you would have already had two so have time from those two to know the side effects.

I think I have been lucky .. everyone reacts differently to things.

I luckily haven’t now bled since dec 2017 - I was on Loestrin 30 for 3 month courses prior to my operation on 2nd March 2018 - then when I had my operation I was still on loestrin 30 then just went straight on to Zoladex.

Definitely nice not having to have that concern of bleeding.



It actually often starts wearing off at 3.5 weeks! And if you do go longer than 28 days, you are likely to get any initial ‘flare’ symptoms again.

There’s also a 12-week form, which you could ask about?


Hi - thanks for the reply.

I had read about the 12 week one - I think they put me in 4 weeks to see how I get on as I can come off it sooner it’s awful.

Are you on zoladex? Do you get a bleed just before you get the next implant?


I used to be on zoladex. I had it for 7 months in 2011 and it was brilliant; but only managed 8 months (of a suggested 2 years) in 2017 as it didn’t downregulate me fully and the HRT was making me anxious.

I’ve never had a bleed at the end of a zoladex implant, no - my first implant of a course will pull my period forward, though, so it falls partway through the implant.

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Hi Sarah, I had a 2 day gap once because the pharmacy made a mess with my prescription. My nurse said a couple of days wasn’t going to affect anything. And I didn’t have any issues that month but everyone is different, I guess. 🤷🏽‍♀️ xx

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