Forfivo XL Side Effects: What to Expect and When to Call Your Doctor

If you've been prescribed Forfivo XL (bupropion hydrochloride 450 mg extended-release), knowing what side effects to expect — and which ones require urgent medical attention — is essential for safe use. This guide covers the full side effect profile of Forfivo XL, from common and manageable to rare and serious.

Boxed Warning: Suicidality in Young Adults

Like all antidepressants, Forfivo XL carries the FDA's most serious warning — a black box warning — regarding an increased risk of suicidal thinking and behavior in children, adolescents, and young adults (under age 25) during the early weeks of treatment. This risk is highest in the first few weeks of therapy and when doses are adjusted. Forfivo XL is not approved for use in patients under 18.

Patients, family members, and caregivers should monitor closely for: increased sadness or hopelessness, new or worsening anxiety, agitation, irritability, unusual behavior changes, or any thoughts of self-harm. Contact a healthcare provider immediately if any of these symptoms emerge.

Common Side Effects of Forfivo XL (5% or more of patients)

The following side effects occurred in at least 5% of patients in clinical trials and at twice the rate of placebo:

Dry mouth: One of the most commonly reported side effects. Stay hydrated and use sugarless gum or candy to stimulate saliva.

Nausea: Usually mild and tends to improve within the first 1-2 weeks. Taking the tablet with food may help, though it's not required.

Insomnia: Difficulty falling or staying asleep is common, especially early in treatment. Taking Forfivo XL in the morning (not evening) can help minimize this effect.

Dizziness: Lightheadedness, particularly when standing up quickly. Usually temporary.

Headache and pharyngitis (sore throat)

Agitation or anxiety: Restlessness or nervousness are known effects, particularly shortly after starting therapy.

Tremor and palpitations

Sweating

Abdominal pain and decreased appetite (anorexia)

Tinnitus (ringing in the ears), myalgia (muscle aches), urinary frequency, and rash

How Forfivo XL Compares: Sexual Side Effects and Weight

One of bupropion's key advantages over SSRIs is its low risk of sexual side effects. Unlike fluoxetine (Prozac), sertraline (Zoloft), or escitalopram (Lexapro), bupropion does not typically cause decreased libido, delayed orgasm, or sexual dysfunction. In fact, bupropion is sometimes used specifically to counteract SSRI-induced sexual dysfunction when added to an SSRI regimen.

Similarly, Forfivo XL is less likely to cause weight gain than many other antidepressants. Some patients experience a modest decrease in appetite or weight loss, particularly early in treatment. This can be beneficial for patients concerned about weight gain from other antidepressants, but patients who are underweight should be monitored carefully.

Serious Side Effects: When to Call Your Doctor Immediately

Seizures: Forfivo XL carries a dose-dependent seizure risk. The 450 mg dose has a higher seizure risk than lower doses. If you experience a seizure, stop taking Forfivo XL immediately and call 911. Do not restart the medication. Report to your prescriber right away.

High blood pressure (hypertension): Bupropion can increase blood pressure. Your prescriber should check your blood pressure before starting Forfivo XL and periodically during treatment. Symptoms of hypertensive crisis include severe headache, chest pain, and vision changes.

Mania or hypomania: Forfivo XL can activate manic episodes in patients with bipolar disorder. Patients should be screened for bipolar disorder before starting any antidepressant. Signs of mania include abnormally elevated mood, decreased need for sleep, racing thoughts, impulsive behavior, and grandiosity.

Psychosis: Hallucinations, delusions, or paranoia are rare but reported. Discontinue the drug and contact your provider if these occur.

Severe allergic reactions: Symptoms like hives, facial swelling, difficulty breathing, or chest pain require immediate emergency care. Rare cases of Stevens-Johnson syndrome (a severe skin reaction) have been reported.

Angle-closure glaucoma: Antidepressants including bupropion have been associated with angle-closure glaucoma. Symptoms include sudden eye pain, redness, and blurred vision — seek emergency care.

Drug Interactions That Increase Side Effect Risk

Certain medications can increase Forfivo XL's side effects or risk of serious events. See our dedicated guide on Forfivo XL drug interactions for a full list. Key interactions include: MAOIs (contraindicated), CYP2B6 inhibitors like ticlopidine and clopidogrel (increase bupropion levels), and other drugs that lower the seizure threshold.

False Positive Drug Tests

An important practical note: Forfivo XL can cause a false positive result on urine drug screens for amphetamines. If you are subject to drug testing (employment, legal, or probation), inform the testing authority that you take bupropion. A confirmatory GC/MS test can distinguish bupropion from true amphetamines.

What to Do If Side Effects Are Problematic

If side effects are significant, contact your prescriber — don't stop the medication abruptly. Many side effects improve within the first 1-2 weeks. Your prescriber may adjust the dose, switch you to a different bupropion formulation, or consider an alternative antidepressant. medfinder can help you locate a pharmacy that has your prescription or an alternative available without delays.