Contrave Side Effects (2026): What's Common, What's Serious & How to Manage Them

The most common Contrave side effects are nausea, constipation, headache, vomiting, dizziness, insomnia, dry mouth, and diarrhea, driven by its two ingredients — the stimulant-like antidepressant bupropion and the opioid-blocker naltrexone. In the Contrave (COR) clinical trials, nausea was by far the most frequent reaction, affecting roughly 32% of patients versus about 7% on placebo, and it is generally heaviest in the first weeks as the dose is increased.^[1] A smaller set of effects is serious and warrants prompt attention: Contrave carries an FDA boxed warning for suicidal thoughts and behaviors (from the bupropion component), a dose-related seizure risk, the potential to raise blood pressure and heart rate, liver injury, angle-closure glaucoma, and dangerous interactions with opioids and MAO inhibitors.^[1] Contrave is naltrexone HCl / bupropion HCl extended-release — it is not a GLP-1 medication like semaglutide or tirzepatide, so its side-effect profile is entirely different. This guide separates what is common and expected from what is rare and serious, explains why the effects happen and how slow titration reduces them, and lays out exactly when to call your prescriber. This is general educational information, not medical advice — your prescriber manages your care.

The most common side effects

The most common Contrave side effects come from its two active ingredients working together. In the placebo-controlled COR clinical trials summarized in the FDA label §6, the reactions reported most often were nausea, constipation, headache, vomiting, dizziness, insomnia, dry mouth, and diarrhea.^[1] These are typically mild to moderate, are most pronounced in the first weeks while the dose is being increased, and tend to ease as the body adapts. Nausea is the standout — it was the most frequent reason patients discontinued Contrave in trials.

• Nausea — the most common reaction by a wide margin, reported by roughly 32% of patients versus about 7% on placebo. Usually worst during the dose-escalation weeks.^[1]
• Constipation — roughly 19% of patients (vs ~7% placebo), driven largely by the naltrexone component's effect on the gut.^[1]
• Headache — roughly 18% of patients (vs ~10% placebo).^[1]
• Vomiting — roughly 11% of patients (vs ~3% placebo), clustering around the early titration steps.^[1]
• Dizziness — roughly 10% of patients (vs ~5% placebo).^[1]
• Insomnia / trouble sleeping — roughly 9% of patients (vs ~6% placebo), reflecting bupropion's stimulant-like, activating profile.^[1]
• Dry mouth — roughly 8% of patients (vs ~2% placebo).^[1]
• Diarrhea — roughly 7% of patients (vs ~5% placebo).^[1]

Other reactions reported more often than with placebo include upper abdominal pain, fatigue, anxiety, hot flush, and tremor.^[1] The table and chart below put the headline rates side by side against placebo so you can see how much of each is drug-attributable.

Why they happen — and how titration reduces them

Contrave combines two drugs with different mechanisms, and the side-effect profile is the sum of both. Bupropion is an aminoketone antidepressant that increases dopamine and norepinephrine signaling — its stimulant-like, activating character explains the insomnia, dry mouth, headache, dizziness, anxiety, and tremor, and it is the component behind the seizure and blood-pressure risks discussed below. Naltrexone is an opioid-receptor antagonist; blocking those receptors in the gut and brain contributes to the nausea, vomiting, and constipation. Together they reduce appetite and food reward, which is the intended effect, but the same pathways produce the gastrointestinal and central-nervous-system reactions.^[1]

This is the entire reason Contrave is titrated up over four weeks rather than started at full dose. The label schedule begins with one tablet each morning in week 1 and adds tablets weekly until the maintenance dose of two tablets twice daily (naltrexone 32 mg / bupropion 360 mg total per day) is reached in week 4.^[1] Climbing gradually lets the gut and nervous system adapt to each step before the next increase, which is why the nausea that hits hardest in the first weeks usually fades. The practical takeaway: rushing the schedule predictably worsens side effects, and Contrave should be taken with food but not with high-fat meals, which can raise drug levels and the seizure risk. When a dose is not tolerated, the move is to discuss it with your prescriber rather than pushing through. See how to get Contrave online for how a legitimate provider sets up and supervises this schedule.

Serious but less common side effects

Beyond the common reactions, the Contrave label lists several serious but less common risks. These are uncommon, but each warrants awareness because several require stopping the drug and seeking care. This is the reason Contrave is a prescription medication taken under medical supervision and not something you self-manage.

• Suicidal thoughts and behaviors (boxed warning). Because Contrave contains the antidepressant bupropion, it carries an FDA boxed warning for suicidal thinking and behavior, along with the risk of neuropsychiatric symptoms — agitation, hostility, depression, mania, anxiety, panic, and unusual mood or behavior changes. Monitor closely, especially in the first months and after dose changes, and stop the drug and seek care if these emerge.^[1]
• Seizures (dose-related). Bupropion lowers the seizure threshold in a dose-dependent way. Contrave is contraindicated in patients with a seizure disorder. Risk rises with higher doses, abrupt alcohol or sedative withdrawal, certain other medications, and conditions or drugs that predispose to seizures. Discontinue and do not restart Contrave in any patient who has a seizure.^[1]
• Increased blood pressure and heart rate. Contrave can raise blood pressure and pulse, sometimes clinically significantly. Blood pressure and heart rate should be measured before starting and monitored during treatment; Contrave is not recommended in uncontrolled hypertension.^[1]
• Hepatotoxicity (liver injury). Cases of liver injury, including hepatitis, have been reported. Stop Contrave and contact a prescriber for symptoms of liver problems — abdominal pain, dark urine, yellowing of skin or eyes (jaundice), or unusual fatigue.^[1]
• Angle-closure glaucoma. The bupropion component can trigger an acute attack of angle-closure glaucoma in susceptible people (those with anatomically narrow angles without a patent iridectomy). Symptoms include eye pain, vision changes, and a red eye — seek care promptly.^[1]
• Manic / hypomanic episodes. Bupropion can activate mania or hypomania in patients with bipolar disorder, and may unmask bipolar disorder. Screening for a history of mood disorders before starting is part of safe prescribing.^[1]
• Opioid and MAOI interactions. The naltrexone in Contrave blocks opioids, so it is contraindicated with chronic opioid use and can precipitate opioid withdrawal; attempting to overcome the blockade with high opioid doses can be fatal. Contrave is also contraindicated with MAO inhibitors (and within 14 days of stopping one) because of the risk of a hypertensive reaction.^[1]

Contraindications recap — who should not take Contrave

The Contrave label lists specific situations where the drug should not be used. A legitimate prescriber screens for every one of these before starting you, and a source that skips that screening is a safety red flag.^[1] Contrave is contraindicated or should be avoided in patients with:

• Uncontrolled hypertension — because Contrave can raise blood pressure and heart rate.^[1]
• A seizure disorder, or a history of seizures — because the bupropion component lowers the seizure threshold.^[1]
• Chronic opioid or opiate-agonist use (or acute opioid withdrawal), and anyone undergoing an abrupt discontinuation of alcohol, benzodiazepines, barbiturates, or antiseizure drugs.^[1]
• Pregnancy — Contrave is not for use during pregnancy because weight loss offers no benefit and may harm the fetus; discontinue if pregnancy occurs.^[1]
• A current or prior diagnosis of bulimia or anorexia nervosa (eating disorders) — because of a higher seizure risk with bupropion in these patients.^[1]
• Concurrent or recent (within 14 days) MAO-inhibitor use, and patients with a known allergy to bupropion, naltrexone, or any component.^[1]

How to manage the common side effects

The common side effects are usually manageable, and most strategies work with the slow-titration design rather than against it. The following are general, commonly-discussed approaches — all of them are prescriber-directed, and you should not change your dose, add medications, or stop Contrave without talking to your clinician.

• Respect the four-week titration schedule. Most nausea and dizziness are heaviest during the escalation weeks and settle once you reach a steady dose. If a step is rough, your prescriber can hold you at the current dose longer before increasing — slower is allowed.^[1]
• Take it with food, but avoid high-fat meals. Taking Contrave with a high-fat meal substantially raises drug levels and the seizure risk, so the label specifically advises against it; a normal meal helps with nausea without that problem.^[1]
• Don't crush, chew, or cut the tablets. Contrave is extended-release; altering the tablet releases the bupropion too quickly and can increase the seizure risk.^[1]
• Manage constipation actively. Adequate fluids, dietary fiber, and movement help; your prescriber may suggest an over-the-counter option.
• Take the second dose earlier if insomnia is a problem. Because bupropion is activating, your prescriber may adjust timing so the later dose is not too close to bedtime — a decision for them, not self-adjustment.
• Avoid alcohol or keep it minimal. Alcohol can interact with bupropion and, with abrupt heavy-drinking patterns, raise the seizure risk; discuss your use with your prescriber.^[1]

When to call your provider — or stop and seek urgent care

Most Contrave side effects are mild and self-limiting, but a defined set of symptoms means contact your prescriber promptly, and some mean stop and seek urgent or emergency care. Use this as a general guide, not a substitute for your clinician's instructions, and when in doubt, call.

• Stop Contrave and seek care immediately for any seizure — and do not restart the drug.^[1]
• Stop and seek urgent care for new or worsening suicidal thoughts, severe agitation, hostility, mania, panic, or unusual mood or behavior changes — the neuropsychiatric symptoms in the boxed warning. Tell family or caregivers to watch for these too.^[1]
• Stop and seek care for signs of a serious allergic reaction (swelling of the face, lips, tongue, or throat; trouble breathing; severe rash) or of liver injury (abdominal pain, dark urine, jaundice, unusual fatigue).^[1]
• Seek prompt eye care for sudden eye pain, a red eye, or vision changes — possible angle-closure glaucoma.^[1]
• Call your prescriber if you have symptoms of high blood pressure (severe headache, chest pain, shortness of breath) or a racing heartbeat, so they can check your readings.^[1]
• Call your prescriber if nausea, vomiting, or constipation is severe or not improving — they can slow your titration or adjust your plan rather than have you push through.

If you are weighing Contrave against other prescription weight-management options, note that it is not a GLP-1 drug — for the injectable GLP-1 class you can compare the best semaglutide providers, or read our reviews of Found and Ro, both of which offer supervised medical weight care. For an overview of treatment options and how prescribing works, start at our medications hub. Whatever you choose, a legitimate provider screens you for the contraindications above, titrates you on the label schedule, and follows up on side effects — exactly the monitoring that keeps Contrave's risk profile manageable.