PT-141 side effects: what the studies found
Real adverse event rates, clinical trial discontinuation numbers, and documented safety warnings from peer-reviewed literature.
This page has not yet been reviewed by a credentialed medical professional. It is educational and is not medical advice.
Safety summary: PT-141
- Evidence level FDA-approved
- FDA approvedYes
- Trial discontinuation18% overall discontinuation due to adverse events in Phase 3 trials (8% specifically due to nausea) vs 2% on placebo.
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In short: The most frequent side effect in clinical trials is nausea, occurring in roughly 40% of patients (and leading to discontinuation in about 8%). Nausea typically begins within an hour and lasts two to three hours. Other common side effects include flushing (20%), headache (11%), injection site reactions (13%), and nasal congestion. Bremelanotide causes a transient increase in blood pressure (averaging 2 to 4 mmHg systolic and diastolic) lasting up to 12 hours, making it contraindicated in patients with uncontrolled hypertension or cardiovascular disease. Focal hyperpigmentation of the face and gums occurred in approximately 1% of patients with repeated use.
FDA Prescribing Warning: Transient increase in blood pressure and heart rate; focal hyperpigmentation risk. Maximum 1 dose per 24 hours and 8 doses per month.
Most common side effects
Reported symptoms in clinical trials and published pharmacology literature:
| Symptom | Reported rate | Clinical context & notes |
|---|---|---|
| Nausea | 40.0% vs 1.3% placebo | Most frequent side effect; led to trial discontinuation in 8% of patients. Typically starts within an hour and lasts 2–3 hours. |
| Flushing | 20.3% vs 0.3% placebo | Facial and chest warmth/redness lasting 1 to 2 hours. |
| Headache | 11.3% vs 1.9% placebo | Transient, generally mild to moderate. |
| Injection site reactions | 13.2% vs 8.4% placebo | Pain, erythema, or pruritus at the subcutaneous injection site. |
| Nasal congestion & cough | 2% to 4% | Mild upper airway symptoms. |
Serious risks and warnings
Potential adverse reactions and biological risks identified in research:
- Transient blood pressure increase: Causes a temporary increase in systolic and diastolic blood pressure (averaging 2–4 mmHg) that can last up to 12 hours. Contraindicated in uncontrolled hypertension.
- Focal hyperpigmentation: Hyperpigmentation of the face, gums, and breasts occurred in 1.1% of patients in clinical trials, especially with more than 8 doses per month and in darker skin types.
Contraindications
This compound should not be used in individuals with:
- Uncontrolled hypertension or cardiovascular disease
- Co-administration with naltrexone (delays absorption)
- Pregnancy (potential fetal harm based on animal data)
Common questions about PT-141 safety
Why does PT-141 cause such high rates of nausea?
PT-141 stimulates melanocortin receptors in the central nervous system, including receptors in the area postrema and solitary tract of the brainstem that regulate the emetic reflex. In clinical trials, 40% of women experienced nausea.
Is the blood pressure increase on PT-141 dangerous?
For individuals with normal blood pressure, the average increase (2 to 4 mmHg) is mild and transient (lasting up to 12 hours). However, in people with pre-existing uncontrolled hypertension or cardiovascular disease, it poses significant risk and is strictly contraindicated.
Can PT-141 cause skin darkening permanently?
In clinical trials, roughly 1% of patients developed focal darkening on the face, gums, or breast tissue after multiple doses. In some patients, the hyperpigmentation did not fully resolve after stopping the medication.