The jobs on your medication calendar
Drug names and brands vary between countries and clinics, but the roles they play are consistent. When your clinic hands you a schedule, try writing the job next to each line.
| Job | Why it is needed | How it is usually given |
|---|---|---|
| Pre-treatment timing (optional) | Helps the clinic schedule the start of treatment | The NHS lists the contraceptive pill or progestogen tablets as an option |
| Suppression | Stops your body from releasing eggs before the clinic can collect them | Daily injection or nasal spray, as the NHS describes |
| Stimulation | Encourages several eggs to mature at once, not just one | Daily self-injected hormone medication (gonadotrophins) |
| Trigger | Completes egg maturation so collection can be timed precisely | A single injection at an exact time; hCG or a GnRH agonist such as leuprolide |
| Lining support | Prepares and supports the uterine lining for an embryo | The HFEA describes this as usually a pessary or gel |
Sources for the table: NHS (reviewed 2025), HFEA (accessed 2026), and ReproductiveFacts (ASRM, 2023) for trigger options.
How the jobs are put together: protocols
The main difference between protocols is how and when suppression happens.
Long protocol
Suppression comes first. According to the NHS, this phase lasts roughly two to three weeks of daily nasal spray or injections, and a scan confirms it has done its job before stimulation is added. On your calendar, this shows up as a block of one drug on its own, followed by a second drug being added.
Antagonist protocol
Stimulation starts first. The HFEA explains that the suppressing medication is then used for a few days after stimulation has begun. On your calendar, you will see stimulation injections alone for the first days, then a second daily injection joining them partway through. Because there is no separate suppression block at the start, the calendar is usually shorter overall.
Mild and natural approaches
Some approaches use fewer drugs. The HFEA describes mild-stimulation IVF as using fewer drugs and natural-cycle IVF as using none, and notes that success rates are lower, significantly so for natural IVF. These can suit particular situations but are not a shortcut to the same results with less medication.
For a side-by-side look at the advantages and drawbacks of each approach, see IVF protocols compared.
Why your protocol and dose are individual
Your clinic chooses a protocol and starting dose based on how your ovaries are expected to respond. The ASRM Practice Committee (2020) notes that AMH and the antral follicle count predict egg yield and the risk of both poor and excessive response well. Age, any previous cycle, your diagnosis and your risk of OHSS all feed in too.
Clinical guidance in this area is detailed and changing. ESHRE updated its guideline on ovarian stimulation in 2025, covering everything from pre-treatment and suppression to monitoring, triggering, lining support and OHSS prevention (ESHRE, 2025). That is one reason two people on "the same protocol" can have quite different calendars.
Reading a calendar: an illustrative example
This is a made-up example to show how to label a schedule. It is not a treatment plan, and it has no doses on purpose.
- Days 1 to 4: one injection each evening. Job: stimulation.
- Day 5: scan and blood test. The dose may change after this.
- Days 5 to 10: stimulation continues, and a second morning injection is added. Job: suppression, so this is an antagonist-style protocol.
- Days 7 and 9: more scans and blood tests.
- Night 10: one injection at an exact time. Job: trigger.
- Collection day: no stimulation drugs.
- After collection: vaginal medication daily. Job: lining support.
Labelling a calendar this way makes it easier to spot mistakes, ask good questions and explain your plan to a local nurse or pharmacist if you are travelling.
When your calendar changes mid-cycle
Calendars are rarely final. Changes usually follow a monitoring result. Common reasons include:
- A dose change if follicles are growing faster or slower than expected
- A different trigger if your response is strong; ReproductiveFacts lists a leuprolide trigger instead of hCG as one way to lower OHSS risk
- Freezing all embryos for a later transfer, another OHSS prevention step ReproductiveFacts describes
- Stopping the cycle if the response is too low or too high to continue safely
Ask the clinic to send each change in writing, with the new dose and the date it starts. Our guide to monitoring bloodwork explains the results behind these decisions.
Practical points
- Timing. Take injections at a consistent time unless told otherwise. The trigger is the one dose where minutes can matter.
- Storage. Check the leaflet for each medicine. Some need refrigeration and some do not, and this matters for travel.
- Technique. Your clinic should teach you how to inject. Our step-by-step self-injection guide covers the details.
- Supplies abroad. If you will be treated in another country, decide early whether you will buy medication at home or at your destination. See getting IVF medications abroad.
Side effects to report
Stimulation drugs are the main cause of ovarian hyperstimulation syndrome (OHSS). ReproductiveFacts notes that about one in three people have mild symptoms such as bloating, nausea or abdominal swelling while stimulating, and that a high AMH or PCOS raises the risk. Mild symptoms are worth mentioning at your next scan. Breathing difficulty, vomiting you cannot stop, or being unable to keep fluids down need a call to your clinic straight away, at any hour.
Common sources of confusion
Most medication problems in IVF are not about the drugs themselves but about the paperwork around them. A few patterns come up again and again:
- Two drugs that look alike. Suppression and trigger injections can share a drug class, and in some protocols the same type of medicine is used for different jobs at different points. Check the job, not just the name.
- Brand names that change. If you buy medication in another country, the brand on the box may differ from the one on your calendar. Ask the clinic to list the active ingredient and strength as well as the brand.
- Dose units. Stimulation doses are usually written in units, not millilitres. If you are unsure how a dose on the calendar translates to the pen or vial you have, ask before injecting.
- Old instructions. After a dose change, throw away or cross out the old schedule so you are only working from one version.
Tell the clinic about everything else you take
Give your clinic a full list of other prescriptions, over-the-counter medicines and supplements before you start. Some may need to be paused or reviewed during treatment, and the clinic can only advise on what it knows about.
Questions to ask about your protocol
- Which protocol am I on, and why that one for me?
- What job does each medication on my calendar do?
- Which test results decided my starting dose?
- What would make you change my dose or trigger?
- Which of my medicines need refrigeration?
- What should I do if I miss or mistime a dose?
- Who do I contact out of hours?
The Takeaway
Label every drug on your calendar by its job: suppress, stimulate, trigger or support. Once you know why each one is there, it is easier to follow the plan, spot changes and ask the right questions.
Frequently asked questions
What is the difference between the long and antagonist protocols?
In the long protocol, suppression medication is used for about 2 to 3 weeks before stimulation, according to the NHS. In the antagonist protocol, the HFEA explains, suppression is added for a few days after stimulation has started, so the cycle is shorter.
Why do I need a trigger injection?
It completes the maturation of the eggs so that collection can be timed precisely. Your clinic will give you an exact time to take it.
Can I choose a protocol with fewer medications?
Mild and natural-cycle IVF use fewer drugs or none. The HFEA notes success rates are lower, significantly so for natural IVF, so discuss whether the trade-off suits you.
Why did my clinic change my dose mid-cycle?
Doses are often adjusted after monitoring scans and blood tests, depending on how quickly follicles are growing and how many are developing.
Is it normal to feel bloated during stimulation?
Mild bloating is common. ReproductiveFacts says about one in three people have mild OHSS symptoms during stimulation. Severe or worsening symptoms need prompt contact with your clinic.