No medical source we checked describes an implantation bleeding smell. A little blood can smell faintly metallic whatever its cause, and vaginal progesterone leaves residue that many people say smells odd. A fishy or strong, lasting smell is what the NHS and other health services link to infection, and that is a reason to ring the clinic.
Listen to this article, about 10 minutes. A synthetic voice reads the article and announces each section title as it begins; tables are read row by row and the questions at the end are left out.
Recorded 19 October 2026 from the article as published that day. Press a chapter to jump there; the highlighted line is what is playing. A play button sits beside every section heading, and once you scroll past this player a bar at the bottom of the screen keeps the controls in reach. Tap or click any sentence to hear the reading start from there.
On this page: a table setting the NHS smell markers beside what two progesterone leaflets say, what 50 Reddit comments from people on progesterone report smelling, and a log for what your clinic says.
Think you already know this? Five questions, one minute.
Every answer is on this page. Answer from what you know now; the page fills in the rest.
-
1. What does the Cleveland Clinic page on implantation bleeding say about smell?
The Cleveland Clinic implantation bleeding page describes light pink or brown spotting that stops in about two days and does not mention smell at all. Read the section
-
2. What does the UK Cyclogest leaflet say about leakage after a pessary dissolves?
The Cyclogest patient leaflet lists leakage after the pessary has dissolved and says this is quite normal for vaginal or rectal medicines. Read the section
-
3. Which smell does the NHS discharge page link to bacterial vaginosis?
The NHS vaginal discharge page says a fishy smell may mean bacterial vaginosis, while normal discharge has no strong or unpleasant smell. Read the section
-
4. Why can a smell not show whether a transfer has worked?
The progesterone given for luteal support is used in every cycle, so its residue, and whatever smell people notice from it, turns up in waits that end either way. Read the section
-
5. According to the Cleveland Clinic, when is a vaginal smell worth getting checked?
The Cleveland Clinic vaginal odour page says to see a provider for a strong or lasting smell or unusual discharge, and that it is especially important if you are pregnant. Read the section
Checked on 19 October 2026 against the NHS pages on vaginal discharge and bacterial vaginosis, the Cleveland Clinic pages on vaginal odour and implantation bleeding, and the UK patient leaflets for two progesterone products, each linked where it is used. This page explains where smells come from during the wait. It does not read any smell as a sign either way, and it cannot: your clinic knows your protocol and your medicines, and this page knows neither.
Does implantation bleeding have a smell?
Not according to anyone who has written it down. The Cleveland Clinic page on implantation bleeding, last updated in August 2024, describes it as very light spotting, “usually pink or brown”, that should stop on its own after about two days. It covers colour, amount and timing. It says nothing at all about smell, and neither does any other clinical source we found.
So where does the idea come from? Mostly from the search box. People notice a smell, notice some spotting, and wonder whether the two belong together. The honest chemistry is dull. Blood contains iron, and the Cleveland Clinic page on vaginal odour says discharge “may smell metallic, like copper pennies” during a period. A few drops of blood from any source can do the same. That faint metallic note says blood is present. It cannot say why the blood is there, which is the only thing anyone in the two week wait wants to know.
If the colour is the question rather than the smell, our page on what implantation bleeding is said to look like covers what the sources say and why none of it settles anything.
Why can things smell different after a transfer?
Because a lot is going on down there that has nothing to do with the embryo. Most IVF protocols add hormones, and many give progesterone as a pessary, gel or capsule placed in the vagina. Those products need something to carry the hormone, and that carrier has to go somewhere once it melts.
- Pessaries. The UK leaflet for Cyclogest 400mg pessaries, last revised in October 2022, calls the base “hard fat” and lists “leakage after the pessary has dissolved”, adding that this is quite normal for medicines inserted this way.
- Gel. The UK leaflet for Crinone 8% vaginal gel, revised in December 2020, says the gel “can stay in your vagina for several days” and may cause a beige to brownish, clumpy or cloudy white discharge, which it says is nothing to worry about.
- The transfer itself. A speculum, a catheter and the gel used to ease them all leave traces, and any spotting from the cervix adds a little blood to the mix.
- Old blood and old residue sitting together. Warmth, time and a panty liner will make almost anything smell stronger than it did an hour earlier.
None of that is a sign of anything except the medicine doing its job of being messy. For what the leaflets and two IVF trials say about the volume of discharge, see our page on discharge during implantation.
Which smells do the NHS and the medicine leaflets flag?
This is the table the ranking pages leave out: what official sources actually say about smell, set beside what the progesterone leaflets say. The striking part is the gaps. Neither UK leaflet mentions odour at all.
| Source, date checked or revised | What it says about smell | What it says to do |
|---|---|---|
| NHS, vaginal discharge, reviewed 15 February 2024 | Normal discharge does not have a strong or unpleasant smell | Get help from NHS 111 if discharge changes, or with itching, soreness or pelvic pain |
| NHS, vaginal discharge | A fishy smell may mean bacterial vaginosis | See a GP if worried; during treatment, the clinic is the first call |
| NHS, bacterial vaginosis, reviewed 19 June 2026 | A strong fishy smell, particularly after sex; discharge may turn greyish white and thin | If pregnant and discharge changes, speak to a GP or midwife |
| Cleveland Clinic, vaginal odour, updated 1 October 2026 | A mild odour is normal; a metallic smell is common during a period; a rotten smell can mean a forgotten object | See a provider if the smell is strong, lasts several days, or comes with unusual discharge |
| Cyclogest leaflet, revised October 2022 | No mention of odour; leakage after the pessary dissolves is quite normal | Tell the doctor, pharmacist or nurse about side effects |
| Crinone leaflet, revised December 2020 | No mention of odour; beige to brownish clumpy discharge for several days | Tell the doctor, pharmacist or nurse about side effects |
| Kaiser Permanente, progesterone vaginal gel | Little white balls of gel are normal and harmless | Report any unusual discharge, itching or odour promptly |
Read together, the sources agree on one thing. A smell on its own is ordinary. A fishy smell, a strong one that lasts several days, or any smell that comes with itching, burning, soreness or a change in colour is the point where a professional takes over. Not one of them describes a smell that means implantation, and not one describes a smell that means the opposite.
What do people on progesterone report smelling?
We read 50 Reddit comments in r/IVF, dated February 2024 to October 2026, from threads about pessaries, gels and odour. These are what people report, not findings, and we have left out every result anyone went on to describe.
- A thread titled Vaginal odor before FET, started in February 2024 and still collecting replies in October 2026, began with a worry about a burnt hair smell days before a transfer. Most of the 15 replies put it down to progesterone in oil injections, with “hamster” and rancid sesame oil the favourite descriptions.
- In January 2026, someone on vaginal progesterone capsules said it barely leaked, but the smell was “wet cardboard meets feta cheese”. It is hard to improve on.
- In February 2026, another described “that weird chemical smell” from suppositories, along with irritation, and said they raised it with their clinic.
- In June 2026, one person found the suppositories easier than expected, with little discharge and no irritation, but said they felt self conscious of the smell.
- Cutting the other way, in August 2026 someone said they had read horror stories about the smell and found their vaginal inserts not bad at all, and in August 2026 another noted grey discharge with no smell, itching or burning, and messaged their nurse.
Across all 50, the pattern was steady. When people mentioned a smell, they blamed the medicine. Threads such as Progesterone pessaries leak were about volume and mess rather than smell. Not one comment we read tied a smell to implantation. That fits the leaflets and the clinical pages exactly: the smell people notice during the wait belongs to the treatment, and the official sources only start to worry when it turns fishy, strong or comes with other symptoms.
Can a smell tell you whether the transfer has worked?
No. There is no smell, and no other symptom, that tells anyone whether a transfer has worked. The progesterone that people blame for the odour is given whatever the outcome, so it turns up in every two week wait, the ones that end well and the ones that do not.
Forums make this look less certain than it is, for a structural reason. People post when something happened to them that they later connect with a result. Hardly anyone writes a thread to say they noticed nothing and the test was positive, or that they noticed everything and it was not. The silent half of the evidence never gets posted. Our guide to why feeling nothing proves nothing covers that missing half, and our page on the honest answer about signs of implantation explains why every symptom list runs into the same wall.
The answer comes from the blood test your clinic has booked, on the day it has booked it. A nose, however well trained by two weeks of forum reading, is not a pregnancy test.
When is a smell a reason to ring the clinic?
This section is written straight.
The NHS lists a fishy smell, discharge that is green, yellow or frothy, thick white discharge like cottage cheese, and discharge with pelvic pain or bleeding as changes that can point to an infection. The NHS page on bacterial vaginosis says there is a small chance it can cause complications in pregnancy, and that it causes no problems in the majority of pregnancies. The Cleveland Clinic says that if you are pregnant, it is especially important to get a strong or lasting smell checked.
During treatment, the call goes to the fertility clinic first, including its out of hours number, rather than straight to a pharmacy counter. The clinic knows which medicines you are on and can decide what is safe alongside them. Ring the clinic about:
- a fishy smell, or any strong smell that lasts several days
- green, yellow, grey or frothy discharge
- itching, burning, soreness or pain when passing urine
- a smell that comes with pelvic pain, fever or bleeding heavier than spotting
The HFEA lists severe stomach pain, swelling, breathlessness and passing little urine as signs of ovarian hyperstimulation syndrome after treatment, and says to contact your clinic immediately. Pain like that is urgent whatever anything smells like.
This page is general information, not personal medical advice. Speak to your fertility clinic or another qualified professional about your own treatment and symptoms.
Two week wait clinic log
A private note kept in this browser only: the date, what you noticed in your own words, and what the clinic said. It records; it does not sort anything into causes.
A fishy or strong, lasting smell, itching, burning or pain belongs with your clinic, which knows your medicines.
Frequently asked questions
Is a metallic smell during the two week wait normal?
The Cleveland Clinic says discharge can smell metallic when blood is present, as during a period. It shows there is a little blood, not where it came from or what it means.
Do progesterone pessaries make discharge smell?
Many people on them say so, but neither of the two UK leaflets we checked mentions odour. Both describe leakage or residue as normal. A smell that worries you is still worth a call.
Is it worth using scented washes or wipes to cover the smell?
Covering a smell also covers the information in it, such as a fishy note the NHS links to infection. Ask the clinic before putting anything new near the vagina during treatment.
Can bacterial vaginosis be treated during IVF?
The NHS says bacterial vaginosis is usually treated with antibiotics. During a cycle, the clinic decides which treatment fits alongside your other medicines, so ring them first.
Why does my urine smell different during treatment?
In the Reddit thread we read, a few people on progesterone injections reported a changed urine smell. Concentrated urine, supplements and infection can all change it too; pain on passing urine needs a call.
Should I mention a smell at the blood test appointment?
If it has not settled or worries you, yes, or ring sooner. Clinics hear about smells and discharge all the time; nothing about it is embarrassing to them.
Finished the page? The same five questions from the top, to see what stuck.
This article is general information, not medical advice, and is not a substitute for care from a qualified healthcare professional. Speak to your doctor about your own situation.
Leave a Reply