Ovitrelle side effects: ovulation, timing and pregnancy tests

For most women the side effects of Ovitrelle are mild: headache, a tender injection site, light cramps and bloating. You get only one injection, so the complaints are short and usually settle within a few days.

There is one thing far more important than the side effects, and it rarely appears large enough in the leaflet. Ovitrelle can make your pregnancy test read false positive for up to ten days. Knowing that spares you one of the nastiest disappointments in the whole process.

What is Ovitrelle and what does it do?

Ovitrelle contains choriogonadotropin alfa, a laboratory made form of hCG. That hormone closely resembles your own LH, the hormone that normally sets ovulation in motion. The injection therefore mimics your natural LH surge.

That is why it is called a trigger. The drug does not grow your follicles, the FSH injections before it did that.

Ovitrelle does one thing: it gives your eggs the final maturation signal and starts ovulation. You get it exactly when your follicles are large enough.

How many hours after Ovitrelle is ovulation?

Ovulation usually follows about 36 to 48 hours after the injection. That is why you often inject at a very specific time, accurate to the quarter hour, with egg retrieval or insemination scheduled about 34 to 38 hours later.

For an IVF retrieval that timing is critical. Too early and the eggs are not mature, too late and you lose them to a spontaneous ovulation.

If you are trying to conceive without a retrieval, many clinics advise intercourse on the evening of the injection and the two days after. Follow your own clinic advice, because protocols differ.

Does Ovitrelle affect a pregnancy test?

Yes, and this is the most important sentence in this article. A pregnancy test measures hCG, and Ovitrelle is hCG. The official product information states that for up to ten days after administration Ovitrelle can interfere with hCG measurement in blood or urine, causing a false positive result.

So if you test on day five after the trigger and see two lines, you may be looking at the remains of your injection. Not at a pregnancy.

There are two ways to see through that:

• Wait until the date your clinic gives you, usually about two weeks after retrieval or insemination
• Have a blood test that reports hCG as a number rather than a line, so a rise becomes visible

That number is the difference. A falling value fits a trigger wearing off, a rising value fits an implantation. Our explanation of hCG doubling time shows how fast that should go, and the hCG calculator compares two results for you.

Side effects of Ovitrelle

The side effects reported most are headache, tiredness, nausea, abdominal pain, tender breasts and a local reaction at the injection site. Because it stays at one injection, they are usually short lived.

Some women mainly notice mood swings and hot flushes in the days after. That fits the hormonal peak you are going through at that moment.

The serious point is hyperstimulation. The trigger is the moment ovarian hyperstimulation syndrome can develop, because hCG keeps stimulating the ovaries for days. Call your clinic if your belly swells quickly, or with severe abdominal pain, vomiting, shortness of breath or clearly reduced urine output.

In women at high risk, clinics therefore sometimes deliberately choose a different trigger or an adjusted schedule. That is a judgement your gynaecologist makes based on your oestradiol and follicle count.

Ovitrelle or Pregnyl: is there a difference?

For your chance of pregnancy, probably not. A Cochrane review of 18 trials with 2,952 participants found no difference between recombinant hCG and urinary hCG in live births, ongoing pregnancies or hyperstimulation (PMID 27106604).

The practical difference is in the form and the administration.

The review team saw slightly fewer injection site reactions with the recombinant form, but that difference did not hold up in sensitivity analysis. Read more at Pregnyl and the timing of ovulation.

Ovitrelle experiences: what do users report?

The picture is strikingly consistent. The injection itself is easier than expected, and the days after are more nerve wracking than heavy.

What women mention positively:

• One injection, ready to use, no dissolving or mixing
• Many women barely notice side effects
• A clear moment where the process turns to the next phase

What comes back as difficult:

• Cramps and a heavy feeling low in the belly in the days after
• Headache and emotional peaks
• The confusion around testing too early

Picture two women who trigger on the same day. One tests on day six, sees a faint line, believes she is pregnant and gets a negative test three days later. The other waits for the clinic blood test. The same treatment, a completely different week.

Which values matter around the trigger?

Just before the trigger the clinic looks at your oestradiol and the number of mature follicles on the scan. Together they decide whether triggering is safe and which drug fits best.

After the trigger it is about hCG and progesterone. hCG shows whether there is an implantation, progesterone whether your luteal phase is sufficiently supported.

You can have the IVF blood test or a separate progesterone test, assessed by a BIG-registered doctor. See also the difference between a blood and a urine test, hCG levels in early pregnancy and the full IVF route.

Frequently asked questions

How long does hCG from Ovitrelle stay in your body?

The product information allows for up to about ten days in which the trigger can disturb an hCG test. In many women it clears sooner, but ten days is the safe limit. So test only on the day your clinic names.

What happens after the Ovitrelle injection?

Your follicles go through their final maturation step and ovulation follows about 36 to 48 hours later. With IVF the retrieval is planned just inside that window. You need do nothing beyond keeping to the time.

What time exactly should you inject Ovitrelle?

At the time your clinic gives you, usually in the evening and accurate to the quarter hour. The retrieval is planned around it. Call your clinic if the timing went wrong, so they can adjust.

How do you store Ovitrelle?

In the fridge as the leaflet describes, although it may be out briefly. Check the leaflet for your own package, because storage times differ per form. Ask your pharmacy if in doubt.

Does Ovitrelle cause twins?

The trigger itself does not raise the chance of multiples. That comes from the number of mature follicles or the number of embryos transferred. That is why the clinic counts exactly how many follicles take part before triggering.

If you remember one thing from this article, let it be the testing. I would not test early, however tempting it is, because a false positive costs more than waiting does. Ask at the trigger which date your clinic plans the blood test and put it in your diary. That one question saves you a week of comparing lines.

Every blood test result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP or your gynaecologist.

References

• Farmacotherapeutisch Kompas. Choriogonadotropin alfa. Accessed 2026.
• European Medicines Agency. Ovitrelle, summary of product characteristics. Accessed 2026.
• Youssef MA, Abou-Setta AM, Lam WS. Recombinant versus urinary human chorionic gonadotrophin for final oocyte maturation triggering in IVF and ICSI cycles. Cochrane Database of Systematic Reviews, 2016. PMID 27106604.
• Al-Inany HG, Youssef MA, Ayeleke RO, Brown J, Lam WS, Broekmans FJ. Gonadotrophin-releasing hormone antagonists for assisted reproductive technology. Cochrane Database of Systematic Reviews, 2016. PMID 27126581.
• Tang H, Mourad SM, Wang A, Zhai SD, Hart RJ. Dopamine agonists for preventing ovarian hyperstimulation syndrome. Cochrane Database of Systematic Reviews, 2021. PMID 33851429.