A mark at an injection site can be easy to forget by the time you speak to a clinician. A reaction log helps you describe what you actually saw and felt, rather than trying to remember it later. Red or itchy skin at the injection site is listed among common semaglutide side effects, but a skin change can have more than one explanation. Treat the log as a record, not a diagnosis.
Start each entry with the injection date and the general area used, following the site wording in your own medicine instructions. Then describe the change in ordinary terms: redness, itchiness, tenderness, swelling, warmth, bruising, or a rash. Record when you first noticed it and whether it was improving, unchanged, or becoming more noticeable later that day or over the next few days.
Keep sensation and appearance separate. For example: "small red area at injection site; itchy on the first evening; no pain; less red next morning." If you take a photo for your own clinical discussion, add the date to your note. A photo should support, not replace, a written timeline and should not be shared publicly.
Look for the pattern across entries. Does the same type of skin change recur, does it last longer, or does it appear with other symptoms? Share that record with your prescriber or pharmacist, especially if the area is spreading, persistent, painful, or otherwise concerning. Ask them any question about how your treatment should be managed.
Seek urgent medical help for signs of a serious allergic reaction, such as swelling of the throat or tongue, a raised itchy rash, or difficulty breathing. Seek urgent help as well for severe or rapidly worsening symptoms.