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Wegovy Injection Site Reactions: When to Call Your Doctor

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At a glance

  • Reported rate / 1.4% of adults on Wegovy 2.4 mg vs 1% on placebo, pooled trials up to 68 weeks [1]
  • What the label instructs / Discontinue Wegovy if a hypersensitivity reaction is suspected [1]
  • Reported after marketing / Anaphylaxis and angioedema [1]
  • Contraindication / Prior serious hypersensitivity reaction to semaglutide or any Wegovy excipient [1]
  • Injection sites / Abdomen, thigh or upper arm; the site can be changed without a dose adjustment [1]
  • Schedule / Once weekly, same day each week, any time of day, with or without meals [1]
  • Absorption / Peak 1 to 3 days after a dose; half-life about 1 week [1]

How common are injection site reactions with Wegovy?

In the label's pooled safety data — three placebo-controlled trials with 2,116 adults on Wegovy 2.4 mg weekly and 1,261 on placebo, treatment up to 68 weeks — injection site reactions were reported in 1.4% of Wegovy-treated patients and 1% of placebo-treated patients [1].

That is below the 2% cut-off for the label's main adverse reaction table, which is led by nausea (44% versus 16%), diarrhea (30% versus 16%), vomiting (24% versus 6%) and constipation (24% versus 11%) [1]. A 2024 review written for emergency clinicians notes that hypersensitivity, including injection site reactions, has been reported with GLP-1 receptor agonists, alongside anaphylaxis and other rashes [2].

What does the label say about allergic reactions?

The Wegovy label reports anaphylaxis and angioedema after marketing and says to discontinue Wegovy and promptly seek medical advice if a hypersensitivity reaction is suspected [1]. Wegovy is contraindicated in anyone with a prior serious hypersensitivity reaction to semaglutide or to any of the excipients in the injection or the tablets [1].

A sore spot does not by itself show whether a reaction is local or allergic. A review for emergency clinicians lists injection site reactions under hypersensitivity, alongside anaphylaxis and other rashes [2], while the label reports anaphylaxis and angioedema separately [1].

Is there a threshold for a local reaction?

The label states no size or duration cutoff for a reaction limited to the injection site [1].

We found no study that tested whether a cold pack, warming the pen before injecting, or an antihistamine taken before the injection reduces these reactions.

Where and how does the label say to inject?

Wegovy goes under the skin of the abdomen, thigh or upper arm, once weekly on the same day each week, at any time of day, with or without meals; the injection site and time of day can be changed without a dose adjustment [1].

The label says to use the injection only when the solution is clear, colorless and free of particles [1].

Frequently asked questions

How common are injection site reactions with Wegovy?
In the label's pooled adult trials of Wegovy 2.4 mg, injection site reactions were reported in 1.4% of treated patients versus 1% on placebo, with treatment up to 68 weeks [1]. That is below the 2% cut-off used for the label's main adverse reaction table [1].
What does the Wegovy label say to do if an allergic reaction is suspected?
The label says to discontinue Wegovy if a hypersensitivity reaction is suspected, and it reports anaphylaxis and angioedema after marketing [1]. A prior serious hypersensitivity reaction to semaglutide or any excipient is a contraindication [1].
Can I use a different spot for each Wegovy injection?
Yes. The label lists the abdomen, thigh and upper arm, and says the injection site can be changed without a dose adjustment [1]. Dosing stays once weekly on the same day each week, at any time of day, with or without meals [1].
Does a sore spot mean I am allergic to semaglutide?
A sore spot does not by itself show whether a reaction is local or allergic. The label reports injection site reactions in 1.4% versus 1% on placebo and, separately, anaphylaxis and angioedema after marketing [1].
What should I check before each Wegovy injection?
The label says to use the injection only if the solution is clear, colorless and free of particles [1].

References

  1. U.S. National Library of Medicine, DailyMed. Wegovy injection and Wegovy tablets (Novo Nordisk) prescribing information. Wegovy injection and Wegovy tablets (Novo Nordisk) label
  2. Long B, Pelletier J, Koyfman A, Bridwell RE. GLP-1 agonists: A review for emergency clinicians. Am J Emerg Med. 2024;78:89-94. GLP-1 agonists: A review for emergency clinicians
Evidence overview for Wegovy Injection Site Reactions: When to Call Your Doctor