Write the stomach bug down as a dated event with a start, a rough end and what happened, then keep your meal-and-symptom entries going beside it. Do not write “bloating because of the bug” or “bloating because of dinner”. At this point you do not know which, if either, is true. A neutral note lets you compare the weeks after the illness with other periods later, which is the only way the diary can say anything useful about it.
This guide is about keeping a record. It cannot tell you whether symptoms are a normal recovery or something that needs assessment, and it does not replace advice from a doctor, pharmacist or NHS 111.
Why the illness belongs in the record
A stomach bug can change the digestive picture around it. Meals eaten during or just after the illness are not comparable with meals eaten when you felt well, and symptoms in the following weeks may or may not be connected to the illness. If the bug is not recorded, a later diary can make an ordinary food look suspicious simply because it was eaten in a different period.
This is the same reasoning as in the guide to which context to record with digestive symptoms: add context when it helps you compare days or exposes another plausible explanation, and write it as an observation rather than a cause.
What to write down
Keep the note short. Four details are usually enough:
- Start date and rough end date. “Sick from Tuesday evening; vomiting stopped Wednesday; loose stools until about Sunday.” An approximate end is fine. If you are unsure, write “unsure when it ended” instead of choosing a date.
- What the illness involved. Vomiting, diarrhoea, fever or stomach cramps, in plain words. You do not need a diagnosis or a name for the germ.
- Anything that may have been shared. If you know others were ill, or where you had eaten, you can note it as something you were told or noticed. It does not need to be a conclusion about the source.
- How eating changed. “Only toast and rice for two days” or “not eating much until Friday”. This matters because your usual meals, which you may later compare, were not the ones being eaten.
You do not need to log medicines, hydration products or doses unless you are already recording them for another reason. Do not start, stop or change a prescribed medicine because of what the diary shows.
Keep the bug as a period, not a single day
An illness tends to blur at the edges. Instead of one dated line, it can help to mark a period in the diary:
- Illness days: the days with vomiting, diarrhoea or other obvious sickness.
- Recovery days: the days when you were eating again but did not feel back to your usual state.
- Back to usual: a day you would call ordinary, written in your own words rather than judged against a standard.
The boundaries are subjective and that is acceptable. The point is to be able to look back and see which entries came before, during and after, not to measure recovery. If you are unsure when you felt back to usual, record the uncertainty. Moving the date later to make a tidy pattern would remove the very information you want to keep.
Keep ordinary entries going
It is tempting to stop writing things down while ill and restart when you feel better. If you cannot manage a diary while unwell, a note saying “ill, not recording” is more faithful than an empty gap. The guide to missing symptom check-ins explains why gaps and their reasons matter when you later compare days.
Once you are eating normally, return to your usual minimal record. The guide to what to record in a food and symptom diary describes a small set of details that is usually enough.
What the research can and cannot tell you
Digestive symptoms can sometimes continue or begin after an infection. A 2024 systematic review and meta-analysis of 47 observational studies, covering 28,170 adults, reported that 14.5% of people who had acute gastroenteritis went on to have irritable bowel syndrome (IBS) at least three months afterwards, and that the odds of IBS were higher than in people who had not had gastroenteritis. The journal later published a correction notice which we could not read in full, so treat the figures as approximate and check the current article if the exact numbers matter to you.
Several limits matter when reading that result:
- It covers adults in observational studies, so it describes groups rather than predicting what will happen to one person.
- It does not mean most people develop long-term symptoms. The same figure means most people in those studies did not.
- It included studies with follow-up of at least three months, some much longer. The review authors also noted that evidence on how the type of germ affects risk is limited.
- It cannot show whether one particular meal, or the illness itself, explains your own symptoms.
The US National Institute of Diabetes and Digestive and Kidney Diseases says that doctors are not sure what causes IBS and lists bacterial infections in the digestive tract among the problems that may contribute. Its page on how IBS is diagnosed lists recent infections among the things a doctor may ask about, which is a reason a clear note of dates is useful to have. Both pages were last reviewed in November 2017.
For the diary, the lesson is modest: a recent infection is a plausible piece of history to keep, and it is not a diagnosis or an explanation.
Reading the weeks that follow
When you review the diary after a bug, look at it as you would any other context:
- Do the symptoms you are curious about appear mostly in the recovery period, and less outside it?
- Did your eating pattern change during that period?
- Do similar meals before the bug and after recovery look different, or similar?
- Are there gaps in the record that make the comparison less fair?
If the answers are unclear, say so. A result that does not separate cleanly is common, as described in what a food diary showing no clear pattern means. Avoid stopping a food because it was eaten in the weeks after the illness. That timing does not show the food was involved, and cutting foods without advice can narrow your diet unnecessarily.
When to get advice
The NHS page on diarrhoea and vomiting says diarrhoea usually stops within 5 to 7 days and vomiting usually stops in 1 or 2 days. It advises calling 111 for bloody diarrhoea or bleeding from the bottom, diarrhoea for more than 7 days, vomiting for more than 2 days, being unable to keep fluids down, or signs of dehydration that persist after oral rehydration sachets. It advises emergency care for vomiting blood or vomit that looks like ground coffee.
For symptoms that carry on, the NHS IBS symptoms page advises seeing a GP if you think you might have IBS and have had symptoms for over 4 weeks. It advises urgent advice for bleeding from the bottom or bloody diarrhoea, a hard lump or swelling in the tummy, or a lot of unexplained weight loss.
A diary does not need to be perfect before you seek care. If you do see a doctor, the dates of the illness and the way your symptoms changed afterwards belong in the story. The guide to summarising digestive symptoms for a GP appointment shows how to turn them into a short history.
GutBloom is designed to keep meals, symptoms and selected context on one timeline while leaving uncertainty visible. If a lower-effort way to keep that record would help, you can get GutBloom on Google Play.
This article was not professionally reviewed.
Sources
- NHS — Diarrhoea and vomiting
- NHS — Irritable bowel syndrome (IBS): symptoms
- Porcari and colleagues, Gut 2024 — prevalence of irritable bowel syndrome and functional dyspepsia after acute gastroenteritis: systematic review and meta-analysis
- Gut 2025 — correction to the Porcari meta-analysis
- National Institute of Diabetes and Digestive and Kidney Diseases — symptoms and causes of irritable bowel syndrome
- National Institute of Diabetes and Digestive and Kidney Diseases — diagnosis of irritable bowel syndrome