The injection will affect each person differently. Some people experience side effects and others don’t. It’s a good idea to keep a record of any side effects that you’re worried about.

These side effects do not affect your health. But they can affect your life, in good or bad ways.

It can cause irregular bleeding

The contraceptive injection changes the pattern of your bleeding. Your periods may stop or you might have irregular bleeding. This is when your bleeding does not happen at the same time each month.

Read more about irregular bleeding.

We sometimes recommend the contraceptive injection for people who have problems with their periods, because it can cause the bleeding to stop. For example, it can be a good choice if you have:

  • premenstrual syndrome

  • heavy periods

  • painful periods

  • endometriosis  

Although some people have no bleeding from the start, irregular bleeding is very common in the first 6 months, and then gradually settles. This is not dangerous in any way:

  • after 3 months of taking the injectable contraceptive, 10% of people have no bleeding  

  • after 12 months of taking the injectable contraceptive, 50% of people have no bleeding

  • 1 in 100 people have ongoing problems with irregular bleeding on the injectable contraceptive – not everyone stops their period

Depending on how it affects you, the change in bleeding pattern may be an advantage or a disadvantage. If you have a lot of irregular bleeding, it can be very inconvenient. If you have very light irregular bleeding, it may not bother you.

I was on the injectable contraceptive for 4 years. My periods got lighter and shorter and then went away completely after about 6 months. This suited me, I don’t miss my periods, but I know it might not suit everyone.

I had a terrible time with the injection. I pretty much bled all the time. I tried for 6 months to get used to it, but it was making my life miserable. I gave up and went back on the pill. One thing that I did like about the injectable was no PMS.

It can cause weight gain

Some people experience weight gain when using the contraceptive injection. This might be because it can increase appetite, so you might feel hungrier and eat more than usual. Weight gain is more common if you are:

  • under the age of 18

  • have a BMI (body mass index) of over 30

If you gain more than 5% of your body weight in the first 6 months of using the contraceptive injection, it's likely you'll continue to gain weight.

Okay, so I'm coming up to a year on the contraceptive injection and I'm getting fat. I love my curves but it's getting too much and my appetite is outrageous. I've been a bit overweight since puberty and I know I put on weight easily. My friend is a gym rat and she seems fine – no difference to her weight at all, if anything she’s lost some.

I was on the Depo shot for about 3 years – started at 15 and stayed on till I was almost 18. I was always petite growing up and couldn’t really put on weight. After the injection, I gained up to 65 pounds and I didn’t really notice until I was having really bad body image issues and not knowing what was different. When I went off of it I lost quite a bit of the weight in about 5 months.

Acne, headaches, hot flushes and vaginal irritation

Acne, headaches, hot flashes and vaginal irritation are some of the symptoms reported by people using contraceptive injections, but they’re also commonly reported by people who aren’t using them.

At the moment there’s no research evidence supporting a link between these symptoms and the injections. But, as with all kinds of contraception, if you get these symptoms and think they’re linked to your injectable contraceptive, you might want to try a different kind of contraception.

Explore different types of contraception.

Mood changes - a review of the evidence

There’s conflicting evidence about whether there’s a link between the contraceptive injection and low mood or depression. Some studies show there’s an increased risk, and others show there’s not an increased risk.

One study followed new contraceptive method users. There was no significant difference in nervousness or depression when comparing users of Depo Provera and users of non-hormonal methods of contraception.

On the other hand, another study found that Depo Provera users had a 44% greater risk of depressive symptoms than those not using it.

Another review of many different published studies didn’t find any evidence linking depression to taking progestogen methods of contraception such as the injection.

The injection made me depressed – I cried out of nowhere, I would be happy one moment and miserable the next. This method was absolutely not for me, everything went back to normal as soon as it ran out.

On Depo I have lost all my PMS and emotional instability – it’s really evened out my moods.

What to do if you experience side effects 

Everyone experiences different types of hormonal contraception differently. If you're getting side effects that you do not like, keep a record of how you feel on it, then try a different method to see whether it’s any better.

Sometimes it can be hard to know if any symptoms you have are because of your contraception or something else.  

We recommend that you: 

  • keep a record of any side effects to see how they change over time

  • discuss it with your clinician, particularly if it carries on after using the contraception for 3 months

  • stop if you have unpleasant side effects over a longer period of time, and try an alternative method of contraception

Sometimes it takes a lot of trial and error before finding the right method of contraception for you. And what’s right for you may change over time. So just because one method suited you in the past, doesn’t mean it will suit you now.

Everything you wanted to know about sexual health and wellbeing - your questions answered by our expert team.