How long do Decapeptyl Side Effects Last For - Endometriosis UK

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How long do Decapeptyl Side Effects Last For

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I had my first ever treatment and diagnosis for Endo on Tuesday and got a Deceaptyl injection.

I am getting a few minor side effects like tiredness, headaches and feeling a bit depressed but also feel I have gotten away lightly compared to some I've read about.

Can anyone tell me if I was going to get anymore side effects, would I have had them by them by now and will my exisiting ones go soon, continally have them or whatever?

Many thanks


5 Replies

Yes you certainly will get more side effects.

The drug overloads the body with hormones in the 1st stages. These reach the pituitary gland in the brain and will in due course cause initially a flare stage probably next week or the week after. this is a surge in hormone activity, can cause extra bleeding, extra pain from endo, extra everything. This flare stage is a normal part of the process.

You can be lulled in to a false sense of security thinking the 1st week is what the whole experience will be like but these are not ordinary drugs. They are chemo hormone drugs.

The flood of hormonal activity in the flare stage to come, will overload and cause the pituitary gland to shut down. This gland under the brain is where many hormones are produced for all sorts of body functions.

The bulk of side effects come about due to a lack of these hormones regulating your body functions, and can change at a moments notice from one minute to the next 24 hrs a day. Sometime you may only be experiencing 2 or 3 side effects and can cope well, other times you'll possibly get 8 or 10 side effects hitting at the same time and really struggle for several hours perhaps days till enough of them calm down and you will not have any idea or much control about what happens and when.

you can opt to take HRT to add back 'some' of the missing hormones, but it cannot replace them all, so while that can help with certain side effects it won't resolve all the side effects.

Here's a list of the hormones produced by the pituitary:

ACTH/ Adrenal glands / Adrenal cortisol production

TSH/ Thyroid gland/ Thyroid hormone production

LH, FSH/ Ovaries, testes/ Reproduction, sexual function

GH (growth hormone)/ Whole body, bones / Growth, body composition

Prolactin/ Breast/ Milk production for nursing

ADH (vasopressin)/ Kidney/ Water, salt balance

And here's just some of the side effects of not having enough of these hormones: (not my own list - I snaffled it from other websites)

ACTH deficiency: this hormone stimulates the adrenal glands to produce cortisol. Cortisol is necessary for life. Lack of adequate cortisol causes fatigue, weight loss, nausea, vomiting, low blood pressure. (It also controls levels of histamine, and without it, if you have an allergic reaction or illness then histamine levels can increase rapidly leading to irritated skin and hives. Anti-histamines can help with this)

TSH deficiency: this hormone stimulates the thyroid gland to produce thyroid hormone. Low thyroid hormone causes fatigue (loss of energy), weight gain, constipation, feeling cold and memory problems. Thyroid hormone regulates body metabolism and is necessary for life. (this one is the hot flushes, cold chills and all the side effects of hypothyroidism also known as under active thyroid)

LH and FSH deficiency: these hormones control the reproductive system and sexual function. Deficiency of these hormones causes loss of menstrual periods and infertility in women and causes loss of sexual function, a low blood testosterone level and infertility in men.

Growth hormone deficiency: Symptoms of decreased energy and vitality are common. Changes in body composition can also occur - more fat is accumulated (especially in the abdomen) and a decrease in muscle mass occurs. There is also a loss of bone density and an increased risk of bone fractures.

Anitdiuretic hormone (ADH (also called vasopressin) deficiency: this hormone is produced by the posterior or back part of the pituitary and is responsible for water and sodium (salt) balance. Deficiency of this hormone causes excessive and frequent urination and excessive thirst. If the patient does not drink an adequate amount of water, the blood sodium can increase abnormally and causes dehydration. Many patients can drink enough water to maintain a normal blood sodium level, but this is extremely inconvenient for the patient - having to drink large amounts of water (day and night) and urinating every hour or so to make up for the large urine losses from the kidneys.

(This last hormone ADH is not normally such a problem with GnRH drugs because production is in part of the pituitary that isn't normally shut down. )

...Of all of all those hormones, the only ones we want to be stopped for endo is the LH hormone. That's the one that sends messages to the adrenal glands, tummy fat and ovaries to produce oestrogen which is what reaches the uterus and the endo cells to remain active.

It seems to me ridiculous to shut off so many other hormones just to target one of them, but that's what happens with GnRH drugs. And the loss of these hormones is what causes side effects. Because each of us is unique in how our bodies will cope being starved of these hormones, the side effects we end up experiencing will vary a lot, and at different times of the day.

At first you body will still retain stocks of some of the hormones and may not notice much change till existing supplies dwindle and are not topped up.

When you stop the drug, it is hoped by you, your Doc and the pharmaceutical company that your pituitary won't take too long getting back up to full production again. But there is no guarantee it will wake up entirely and get all the hormones back in production.

Some may not get back in enough supply to stop you having the side effects associated with it, which is why some patients ( a surprisingly high number)end up with long term side effect problems.

In my own case all side effects eased off except short term memory loss. it's nearly 3 years since i stopped zoladex and it is still a problem i have each and every hour of the day.

For other ladies it could be an ongoing problem with growth hormone, or their ovaries don't wake up due to shortage of LH etc.

some side effects like the hot sweats/cold chills just fluctuate from one extreme to another, and you may get one or two an hour or anything up to 6 or more flushes an hour day and night. At least that is something HRT can help with.

Please read the patient advice leaflets on GnRH drugs and let family members know what it can do to you so you are not caught by surprise, and get the support you may need at times to cope with it.

Unlike cancer patients on the same drugs who can get extra support and advice from Macmillan nurses there is no such provision for ladies with endo on the same drugs, so you do have to do your own homework and hopefully then you wont get too surprised when a new side effect suddenly manifests itself out of the blue.

The patient info sheet is on a pdf through this webpage

How severe you feel them, how frequently they hit you, how long they stay is unique to each patient.

On GnRH, the list of some of my side effects (that I can list off the top of my head) are Tummy upsets, blurred vision days (can't drive or read or watch tv), hair loss (about a third of head hair and most of the body hair), itchy skin, hives, sore muscles and veins and bone pains, dizzy spells, palpitations, panic attacks, depression, sensitivity to lights and sounds and extreme irritability and teenage tantrum like mood swings which were evil for everyone else and i had no control over them which is very our of character for me, hot flushing followed by a freezing cold chill about 6 an hour every hour day and night, so a hot flush roughly every 10 minutes. forgetfullness. I mean a complete absence of making memories, i kept a diary by the bed and wrote down my symptoms and everything else because I just couldn't remember things. 1st notices when I missed the appointment for the next implant and the clinic phoned up. It wasn't deliberate, but apparantly they had called about a week earlier to change the appointment time, and spoke to me, but I have no recollection at all of that phone call. Mum says she remembered them calling and me telling her that the time had changed, but didn't matter I still forgot it all. I would forget if I had eaten a meal, and certainly forget what I had eaten. mum took over making sure that I ate regular meals, otherwise I tended not to eat. I did have to up the drinking a lot because of the dehydration from the hot sweats.

I was pretty much bed bound for month 3 and 4, didn't react well to the drug at all, but I can't say t will be as bad as that for everyone, it certainly will be bad for many, but by some miracle there are other ladies who do cope a lot better and do not have such a bad time over all.

don't be complacent and expect weeks 1 and 2 to reflect the entire time on these drugs, it really is just the start. Wait till the next implant is due, by which time the flare stage will have shut things down and you will have a better idea about whether you want to risk another month or not.

In hindsight i should have stopped after the 3rd one. I did stop after the 4th. But knowing what i have had to put up with since then, I shouldn't have taken it at all.

You cannot predict how you will react till you try it. Cuddlybarb, a member of the forum, was a very reluctant user of Decapeptyl, and like you reported all was well a couple of weeks in to it, I think she did have no.2 dose as well, but stopped there because she found the experience became too much to bear. She did have all the information in advance and did her homework before deciding to start, so in many respects she was very well informed, but even though she knew what could happen, it was still a shock when it did actually hit her.

I really do wish you all the luck in the world, it won't be a doddle, but with luck it won't be as bad as it is for some of us. It doesn't matter which GnRH drug you are on as they all do the same thing in flooding the pituitary gland with hormones that shut it down, and the side effects come from the shutting down, so switching GnRH will make no difference to how your body reacts. These drugs are not like anything your body will have had before drug wise.

1 like
in reply to Impatient

Thanks for taking the time to write to me and sharing your experience. I hope things are better for you at the monent x


Good Afternoon hope you are well today

I am looking for some advice really I had my lap December last year and endo was discovered some was burnt off, but I also have endo growing on my bowel. I have been put on Decapeptyl injections had my first in december and got my second in march. I am also on HRT amd I also have an implanon implant in my arm, which my consultant said to leave in. I visited my doctors last week for some routine blood tests and it was discovered that my prolactin levels are 700 which my GP thinks is way too high. My own GP thinks I am on too much hormone treatment with everything I am on. I am not feeling great and still in a lot of pain.

I am getting knowhere with my consultant

Can anyone offer any advice please

Many thanks for your help much appreciated

Love Janet

in reply to Impatient

Thank you so much for this information, I was searching the forum for info on Prostap as I am now in the 2nd month with 3rd injection this week. After the initial flare it seemed to be working very well with little side effects, however I then caught a cold which took forever to clear and I am now suffering with a lot of aches and pains in my shoulders particularly but neck, arms and hips too, as well as an increase in constipation (I have ibs anyway but this is worse than normal). The information about the different hormones has been really insightful as I feel this could well be the problem, I am not on any HRT with the Prostap but if these side effects continue I may ask for some. Thanks again for sharing this info, and hope things are better for you now!


Hey I also thought that at first I'm now 3 weeks in to my second 12 week injection. The first week I felt ok then in the second and third week I had constant headaches. I had no flare up bleed but did have a flare up of pain, by the beginning of the fourth week everything settled down. I have sufferen from hot flushes, night sweats and the odd headache since then but nothing that I can't handle. I'm really glad I went through with them! 9 weeks to go for me. I wish you all the best and hope for as little side effects as possible! I also have not been using hrt but I was offered to start this if side effects became unbearable.

Danielle xxx


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