What the label lists and what reports show
Histrelin side effects
Histrelin's FDA label: “The most common adverse reaction is implant site reaction (51.1%), including complications related to the insertion or removal of the implant ( 6 ).” FAERS holds 875 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is device breakage (117 reports).
- No generic listed
Check it at the source: the histrelin FDA label on DailyMed (effective September 25, 2025, Endo USA, Inc.); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of SUPPRELIN LA?SUPPRELIN LA may cause serious side effects. See “What is the most important information I should know about SUPPRELIN LA?” The most common side effect of SUPPRELIN LA includes skin reactions at the place where the implant is inserted. These reactions may include pain, redness, bruising, soreness, and swelling in and around the implant site. Call your child’s doctor if your child has bleeding, redness, or severe pain where the implant was inserted. These are not all the possible side effects of SUPPRELIN LA. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Source: FDA drug label, Endo USA, Inc., effective September 25, 2025 (SPL set d8fb000e-3cc9-4803-b71d-2cc597661977), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common adverse reaction is implant site reaction (51.1%), including complications related to the insertion or removal of the implant ( 6 ).
Table 1: Incidence of implantation adverse reactions reported by ≥ 2 patients treated with SUPPRELIN LA in both clinical trials
| Adverse Reactions | N=47 N (%) |
|---|---|
| Implant site reaction | 24 (51.1) |
| Keloid scar | 3 (6.4) |
| Scar | 3 (6.4) |
| Suture related complication | 3 (6.4) |
| Application site pain | 2 (4.3) |
| Post procedural pain | 2 (4.3) |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following serious adverse reactions are described here and elsewhere in the label: Initial Agonist Action [see Warnings and Precautions ( 5.1 )] Implant Breakage [see Warnings and Precautions ( 5.2 )] Psychiatric Events [see Warnings and Precautions ( 5.3 )] Convulsions [see Warnings and Precautions ( 5.4 )] Severe Cutaneous Adverse Reactions [see Warnings and Precautions ( 5.5 )] Pseudotumor Cerebri (Idiopathic Intracranial Hypertension) [see Warnings and Precautions ( 5.6 )] The most common adverse reaction is implant site reaction (51.1%), including complications related to the insertion or removal of the implant ( 6 ). Adverse events related to suppression of endogenous sex steroid secretion may occur ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact Endo at 1-800-462-3636 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Overall Adverse Reaction Profile The most common adverse reactions with SUPPRELIN LA involved the implant site. Local reactions after implant insertion include bruising, pain, soreness, erythema and swelling. During the early phase of therapy, gonadotropins and sex steroids rise above baseline because of the natural stimulatory effect of the drug.
Source: FDA drug label, Endo USA, Inc., effective September 25, 2025 (SPL set d8fb000e-3cc9-4803-b71d-2cc597661977), via openFDA; the full label on DailyMed
What do FAERS reports show?
875 reports list histrelin among the medicines taken, each a report of something that happened, not proof the medicine caused it; 28 are coded as a death and 48 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 22 reactions below, 7 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Histrelin: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions