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Dr. Chrysoula I. Liakou MD, PhD
- Treated online: Assessment online. A doctor can check whether the injection suits you and plan cover if one is late; the injection is given in person.
- How long it lasts: most people have an injection every 13 weeks; one given up to 14 weeks after the last still protects you.
- How well it works: over 99% effective when every injection is on time; with typical use, about 6 in 100 users become pregnant in a year.
- Periods and fertility: almost half of users have no periods after a year, and fertility can take up to a year to return after stopping.
- Emergency: call 112 for swelling of the face, lips or throat or difficulty breathing after an injection, or chest pain, breathlessness or a painful swollen leg.
Call 112 or go to an emergency department for swelling of the face, lips or throat, wheezing or difficulty breathing after an injection, or for chest pain, sudden breathlessness or a painful, swollen leg. If your injection is more than a week late and you have had unprotected sex, emergency contraception works best the sooner it is taken.
Can an online doctor help with the contraceptive injection?
No, the injection cannot be given online: it is given by a nurse or doctor, or by yourself once you have been trained in person to inject under the skin. What a doctor can do by video is check whether it suits you, explain the side effects honestly, plan cover if an injection is late, prescribe a bridging method or emergency contraception when needed, and tell you when to be seen in person.
How an online consultation helps with the contraceptive injection
- Is it right for you?: Bleeding, weight, bone health and the return of fertility, weighed against the other long-acting methods.
- Late for your injection: Whether you are still protected, whether you need emergency contraception, and cover until the next one.
- Side effects reviewed: Bleeding that will not settle, weight gain or mood changes, and what can help.
- Planning ahead: When to switch at 50, what to use before trying for a baby, and how to stay covered.
What the doctor checks in an online contraceptive injection consultation
The doctor asks about the warning signs first, then about your health and how you use the injection. The doctor asks about:
- Warning signs: heavy bleeding, pain, swelling or pus at the injection site, or a chance you are pregnant.
- Your health: breast cancer, heart disease or stroke, liver or long-term kidney disease, blood clots, unexplained bleeding between periods or after sex, and risk factors such as smoking, diabetes or high blood pressure.
- Bone health: your age, how long you have used the injection, and risk factors for weak bones.
- Your plans: whether you might want to become pregnant in the next year or two.
- Your injections: the date of the last one, and whether you have unprotected sex since it was due.
- Weight and mood: changes since you started.
Before the call, find the date of your last injection. If it is late, note when you last had unprotected sex.
What is the contraceptive injection, and how long does it last?
The contraceptive injection contains a progestogen, most often medroxyprogesterone acetate, and works mainly by stopping ovulation. Depending on the type, it lasts 8 to 13 weeks; the most common one is given every 13 weeks, either into a muscle by a nurse or doctor, or under the skin, which you can learn to do yourself.
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| Situation | What it means | What to do |
|---|---|---|
| Started on days 1 to 5 of your period | Protected from the start | Nothing more |
| Within 21 days after giving birth, or straight after a miscarriage or abortion | Protected from the start | Nothing more |
| Started on any other day | Not protected straight away | Use condoms for 7 days |
| Next injection up to 14 weeks after the last | Still protected | Have it as soon as you can |
| More than 14 weeks after the last, with unprotected sex | You may not be protected | Emergency contraception (a copper IUD or levonorgestrel), condoms for 7 days after the injection, and a pregnancy test 3 weeks after the sex |
How effective is the contraceptive injection?
Over 99% effective when every injection is on time; about 2 in 1,000 users become pregnant in the first year with perfect use. With typical use, including late injections, about 6 in 100 become pregnant in a year, compared with about 7 to 9 in 100 on the combined pill.
Is the injection better than the pill?
It depends on what matters to you. The injection needs remembering only 4 times a year, so it works better in everyday life than daily pills, and it often stops periods. The pill is easier to stop and its effects wear off quickly, while the injection can delay the return of periods and fertility and causes a small loss of bone density.
Does the contraceptive injection stop periods?
Often, yes, but not straight away. Bleeding changes are common at first: periods can become irregular or longer. The longer you use the injection, the more likely your periods are to stop: about 1 in 10 users have no bleeding in the first 3 months, rising to almost half after a year.
Having no periods on the injection is safe and reversible, although periods can take a few months to come back after you stop. Bleeding that bothers you is worth a review: an anti-inflammatory medicine can shorten an episode, and the breakthrough bleeding page explains the other options.
Side effects and risks of the contraceptive injection
The most common side effects are changes in bleeding and weight gain. Some people report headaches, mood changes, acne, a lower sex drive or hot flushes, although there is not enough evidence to say whether the injection causes them. Pain, a small lump or a scar can form where the injection was given.
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| Risk | What is known | What it means for you |
|---|---|---|
| Weight gain | Common; gaining more than 5% of your weight in the first 6 months makes further gain likely | A review if you gain weight early on |
| Bone density | A small loss with use for more than a year, largely recovered after stopping | A review at least every 2 years; a switch is usually advised at 50 |
| Return of fertility | Can take up to a year after the last injection | Plan ahead if you want a baby in the next year or two |
| Breast cancer | A possible small increase in risk with current or recent use; the absolute risk is very low | Discussed with your history |
| Blood clots | Some studies report an increased risk; it has not been shown to be caused by the injection | Another method may be advised after a clot |
| Meningioma, a non-cancerous brain tumour | A small increased risk | Discussed with your history |
| Allergic reaction | Rare | Have another adult with you when you inject yourself |
What are the disadvantages of the contraceptive injection?
You cannot stop it working once it has been given: side effects can last until it wears off, and fertility can take up to a year to return. It can cause weight gain and a small loss of bone density, needs an appointment or self-injection every 13 weeks, and does not protect against sexually transmitted infections.
Does the contraceptive injection help acne?
It is not a treatment for acne. Some users report acne, but there is not enough evidence to say whether the injection causes or improves it. The acne page covers what does help.
Can you still get pregnant on the injection?
Rarely, if your injections are on time: about 2 in 1,000 in the first year. Most pregnancies happen when an injection is late, which is why the timing matters.
What might the doctor recommend about the contraceptive injection?
This is the framework the doctors use, in line with UK sexual health guidance:
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| What you have | Likely first step | Suitable for online care? | When in-person care is needed |
|---|---|---|---|
| You want a method you do not take every day | A suitability check, including bone health and plans for a baby | Yes, to assess | For the injection |
| Injection late by up to a week | Have it as soon as you can; still protected | Yes | For the injection |
| Injection more than a week late, with unprotected sex | Emergency contraception and a pregnancy test plan | Yes | For the injection, or a copper IUD |
| Bleeding that bothers you | An anti-inflammatory medicine, or a short course of the combined pill if it is safe | Yes | If bleeding follows sex or will not settle |
| Weight gain early on | A review of whether another method suits you better | Yes | Not usually needed |
| Used for 2 years or more, or reaching 50 | A review of bone health, and switching methods if needed | Yes | For any tests |
| Pain, swelling or pus at the injection site | A check for infection | Partly | For an examination |
| Swelling of the face or throat, or difficulty breathing | Emergency care | No | Call 112 now |
Not sure whether the injection is right for you? A doctor can tell you in one consultation.
See available times →Contraceptive injection care and options
What you can do yourself
- Put the date of your next injection in your calendar, with a reminder a week before.
- If you inject yourself, have another adult with you, in case of a rare allergic reaction.
- If you want to become pregnant in the next year or two, plan your switch early: fertility can take up to a year to return.
- If you do not want a pregnancy, start another method before or at your next due date when you stop, even if you have no periods.
- Use condoms with new partners: the injection does not protect against sexually transmitted infections.
Prescription treatment
A prescription is never issued without a consultation. The injection itself is given in person, but around it the doctor may prescribe a method to cover you until your appointment, such as the progestogen-only pill, emergency contraception if an injection is late, or treatment for bleeding that bothers you, when it is safe for you. If the injection does not suit you, the doctor can talk you through the alternatives. If the doctor prescribes, use the prescription at a pharmacy near you.
What does not help
Having injections closer together to improve bleeding, which has no evidence behind it. Stopping without another method in place. Waiting for your periods to return before using contraception.
Special situations
Breastfeeding and after a birth
The injection is safe while breastfeeding and does not affect your baby or your milk. Given within 21 days of the birth, it protects you straight away.
Under 18 or over 45
Under 18, the injection can be used after the alternatives have been considered, because of its effect on bone density. Most people are advised to switch to another method at 50, and the contraception in perimenopause page explains the options.
When oestrogen is not suitable
The injection contains no oestrogen, so it can be an option when the combined pill is not, for example with migraine with aura. The doctor checks this against your full history.
Living or travelling abroad
Plan your next injection around your trip: it can be given from 10 weeks after the last one if you will be away when it is due. If you are abroad and late, a doctor by video can plan cover until you can have it.
Children
Mobi Doctor consultations are for adults aged 18 and over. A child who is unwell needs a paediatrician or a local doctor in person, and emergency signs in a child mean 112.
When the contraceptive injection is assessed online, and when you need in-person care
Assessed online: choosing a method, late injections and emergency contraception, bleeding, weight and mood reviews, bone health reviews, and planning a switch or a pregnancy.
In-person care: the injection, or training to inject yourself, examinations of the injection site, and any test the doctor recommends.
When to get in-person care
Call 112 or go to an emergency department now for:
- swelling of the face, lips, tongue or throat, wheezing or difficulty breathing after an injection
- sudden chest pain, sudden breathlessness, or coughing up blood
- a painful, swollen leg
Get medical advice the same day for:
- pain, redness, swelling or pus at the injection site that is getting worse
- an injection more than a week late with unprotected sex since it was due
- a positive pregnancy test while using the injection
- very heavy bleeding
How Mobi Doctor works
- Book a time that suits you: daily 7am–11pm CEST. You can see a doctor over video, usually within 15 minutes. No subscription, and the exact price is shown before you pay.
- Speak to a licensed doctor about the injection: give the date of your last injection, say what you have noticed, and mention any plans for a pregnancy.
- Leave with a plan: what to do, what to take and for how long, and which signs mean you should be seen in person. If the doctor prescribes, use the prescription at a pharmacy near you.
No sign-up needed
Noticed a new symptom on the contraceptive injection? Tick every symptom you have to see each condition page that mentions it. It finds the right page, not a diagnosis: a doctor gives you that on a video call.
Tap the body — an area or a point — to browse symptoms anywhere
Similar symptoms, different condition? Contraceptive Implant can start the same way. Compare them, or look up any other symptom in the full symptom checker.
Frequently asked questions about the contraceptive injection
How long does the contraceptive injection last?
Most injections last 13 weeks, and an injection given up to 14 weeks after the last one still protects you. Depending on the type, an injection lasts 8 to 13 weeks.
How effective is the contraceptive injection?
Over 99% effective when every injection is on time. With typical use, including late injections, about 6 in 100 users become pregnant in a year.
Does the contraceptive injection stop periods?
Often, the longer you use the injection: about 1 in 10 users have no bleeding in the first 3 months, rising to almost half after a year. Irregular or longer bleeding is common at first.
What are the side effects of the 3-month injection?
Changes in bleeding and weight gain are the most common side effects of the injection. Some people report headaches, mood changes, acne or a lower sex drive. Use for more than a year causes a small loss of bone density, largely recovered after stopping.
Does the contraceptive injection cause weight gain?
It can: weight gain is a common side effect of the contraceptive injection. Gaining more than 5% of your weight in the first 6 months makes further gain likely, so that is a good time for a review.
What are the disadvantages of the contraceptive injection?
Once the injection has been given, it cannot be stopped, fertility can take up to a year to return, it can cause weight gain and a small loss of bone density, and it does not protect against sexually transmitted infections.
What can I do at home about side effects of the contraceptive injection?
Keep a diary of bleeding so the doctor can see the pattern; irregular bleeding on the injection often settles with time, and an anti-inflammatory painkiller can shorten an episode. Weigh yourself in the first 6 months, because early weight gain predicts more. Keep calcium and vitamin D in your diet and stay active to protect your bones, and use condoms with new partners, since the injection does not protect against infections.
Is the injection better than the pill?
It works better in everyday life, because you only need it every 13 weeks, and it often stops periods. The pill is easier to stop and its effects wear off quickly, while the injection can delay the return of fertility and causes a small loss of bone density.
Contraceptive injection or implant: which is better?
Both are progestogen-only and over 99% effective. The implant lasts 3 years, can be removed at any time with fertility returning at once, and does not affect bone density; the injection lasts 13 weeks, cannot be reversed once given, can cause weight gain and a small loss of bone density, and fertility can take up to a year to return. The injection suits people who want nothing fitted under the skin and no daily routine.
Can you still get pregnant on the injection?
Rarely, if your injections are on time: about 2 in 1,000 users become pregnant in the first year. Most pregnancies on the injection happen when one is late, which is why the timing matters, so if you are more than a week late and have had sex, get emergency contraception and a pregnancy test plan.
How long does it take to get pregnant after stopping the injection?
After the last injection it can take up to a year for fertility to return, so plan ahead if you want a baby. If you do not, start another method before or at your next due date.
What happens if my injection is late?
Up to 14 weeks after the last injection, you are still protected. Later than that, if you have had unprotected sex, you may need emergency contraception, condoms for 7 days after the next injection, and a pregnancy test 3 weeks after the sex.
Can an online doctor give the contraceptive injection?
No, it is given in person, or by yourself after training. A doctor by video can check whether it suits you, plan cover if an injection is late, and prescribe a bridging method or emergency contraception.
- What is the contraceptive injection?, NHS, National Health Service (UK), reviewed 8 February 2024.
- Contraceptive injection: side effects and risks, NHS, National Health Service (UK), reviewed 8 February 2024.
- Contraceptive injection: who can get it, NHS, National Health Service (UK), reviewed 8 February 2024.
- FSRH Clinical Guideline: Progestogen-only Injectable Contraception, Faculty of Sexual and Reproductive Healthcare (now the College of Sexual and Reproductive Healthcare), December 2014, amended July 2023.
- Problematic bleeding with hormonal contraception, Faculty of Sexual and Reproductive Healthcare (now the College of Sexual and Reproductive Healthcare), Clinical Effectiveness Unit, July 2015.
- How can I stop my periods?, Contraception Choices, College of Sexual and Reproductive Healthcare (UK), accessed 15 October 2026.
- FSRH Guideline: Combined Hormonal Contraception, Faculty of Sexual and Reproductive Healthcare (now the College of Sexual and Reproductive Healthcare), January 2019, amended October 2023.
This page is for information only and is not a substitute for a medical consultation. Guideline links are provided for transparency; treatment decisions are made with your doctor.
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