How to track GLP-1 side effects in a diary

Why timing and context matter

Timing and context turn a vague memory into something your doctor can work with. “Some nausea last week” is hard to use. “Mild nausea on Tuesday and Wednesday, two and three days after my dose, after big lunches” gives your doctor real questions to ask. Come appointment time, notes like that slot straight into a one-page progress report for your doctor.

Nausea, vomiting, diarrhea, constipation and stomach pain can have many causes. Some are listed as common side effects of GLP-1 medicines. MedlinePlus lists them for both semaglutide and tirzepatide. But a date next to a symptom doesn’t prove the medicine caused it. A stomach bug, a rich meal or a bad night’s sleep can look the same on paper. That’s why context matters.

Write what happened first. Save your guesses for later, or for your appointment. “Loose stools twice in the afternoon; drank less water than usual” is more useful than “the medication is upsetting my stomach.”

What to include in a symptom entry

A good entry answers five quick questions: what, when, how strong, how often and what else. You don’t need all of them every time. A short entry you actually write beats a perfect one you skip.

• Symptom: use your own words. Say where in the body, if it helps.
• When: the day, and roughly when it started and stopped. Note if it’s still going.
• How strong: use the same simple scale every time, like mild, moderate or severe.
• How often: count the times it happened, not just the worst one.
• Daily context: meals, drinks, sleep, activity, stress, or being ill. Anything that helps you remember the day.
• Dose day: the date of your last prescribed dose, so you can count the days since. Write down questions, too.
• Who you talked to: if you called your doctor or pharmacist, note what they said. Keep their guidance separate from your own notes or anything an app shows you.

Redness, itching or a bruise where you injected counts too. Write the site next to it, and if it keeps happening, an injection site rotation log puts all your sites in one place. For the meals part of your daily context, our guide to tracking protein and fiber on a GLP-1 keeps it to a quick tally.

What does a week of entries look like?

A week of entries can fit on one page: one row per day, with the symptom, how strong it was and a short note. Here is a made-up example for someone whose dose day is Monday. Quiet days count, too. A blank row tells your doctor something.

Notice what the example does not do. It doesn’t say “the medicine caused this,” and it doesn’t plan any change. It just records the week, so the conversation at your next visit starts from facts.

How do you rate how strong a symptom was?

Pick a simple three-step scale and use it the same way every time. The exact words matter less than being consistent, because your doctor will compare your weeks with each other, not with someone else’s.

One way to describe the steps, in everyday terms:

• Mild: you notice it, but your day goes on as planned.
• Moderate: it changes your plans. Maybe you eat less, rest more or leave early.
• Severe: it stops you from doing what you normally do.

This scale is only for your notes. It isn’t a medical test, and it doesn’t tell you whether a symptom is serious. If a symptom feels serious to you, read the next sections and reach out for help.

How to read your diary

Look at the diary a week or a month at a time, not one day at a time. Patterns only show up over several weeks. One bad day on its own says very little.

When you look back, try these questions. They help you spot things worth mentioning, without jumping to conclusions:

• On how many days did you log a symptom this week? Is that more or less than last week?
• Do symptoms tend to show up on the same days after your dose?
• Do they show up after certain meals, short nights or low-water days?
• Did anything else change, like a new routine, travel or an illness?
• What question do you want to ask at your next appointment?

Bring the answers to your visit. A one-page summary works well, with your diary next to your doses, weight and meals. If you want to compare symptom days with the curve in your app, our guide to how PenPal’s estimated medication level is drawn explains what that estimate can and can’t tell you.

Common diary mistakes

Most diary problems come from writing too much, too late or too unevenly. These are easy to fix:

• Writing from memory days later. Details fade fast. A quick note on the day beats a long one on Sunday.
• Only logging bad days. Quiet days show what “normal” looks like for you.
• Changing your scale. If “moderate” meant one thing in March and another in May, the trend gets muddy.
• Mixing facts and guesses. Keep what happened separate from what you think caused it.
• Leaving out context. Without meals, water and sleep, a symptom has no story around it. A weekly weigh-in can sit alongside too; our guide to tracking your weight on a GLP-1 keeps that calm.
• Keeping it to yourself. A diary helps most when you share it at your appointment.

When should you contact a professional?

Contact your doctor or pharmacist if a symptom is severe, getting worse, won’t go away, or worries you. Don’t wait for your next scheduled visit, and don’t wait to “see the pattern” in your diary first.

Your medication guide and your doctor’s instructions come first for warnings about your specific product. MedlinePlus lists symptoms that need a doctor right away for semaglutide injection and tirzepatide injection. These include stomach pain that won’t go away, signs of an allergic reaction such as swelling of the face or throat, and trouble breathing or swallowing.

If you think you might be having an emergency, such as trouble breathing or fainting, call your local emergency number. Don’t wait for a website, an app or an email reply.

Don’t use the diary to change doses

A diary shows what happened. It can’t tell you what to do next. Don’t stop, restart, repeat or change a dose based on a diary or an app. Those choices belong to you and your doctor, together. If a symptom makes you wonder about your dose, write the question down instead, like “Nausea on days 2 and 3 again this week. Ask about it at my visit.”

Exact instructions matter here. The FDA has warned about dosing errors with some compounded injectable semaglutide products. Follow the instructions from your doctor and pharmacist for the product you actually have.

How PenPal can organize the notes

PenPal records each symptom, how strong it was and which day it happened, on the same timeline as your doses, meals, water and weight. It also shows which day after your dose it is. It doesn’t decide whether a symptom is a side effect, and it doesn’t give medical advice.

• Body Check-In: tap a symptom such as nausea, fatigue, headache, reflux or constipation, then pick mild, moderate or severe. Not on the list? Add your own.
• Day after dose: the check-in card shows which day after your last logged dose it is, such as “Day 3 after dose.”
• Weekly insights: see which side effects showed up most this week, and on how many days.
• PDF report: add your side effects to a progress report for the dates you choose. It lists each symptom, how many days you logged it, the worst strength, and the typical day after your dose.

PenPal keeps the quick part quick. Extra detail, like how long a symptom lasted, can go in your own notes and come along to your visit. See how the GLP-1 side effect tracker works, or start with the bigger picture in what a GLP-1 medication tracker records.