Key Takeaways
- Prozac can start to show improvement in sleep, energy, or appetite within one to two weeks.
- Full improvement in a person’s mood and interest in daily activities may take six to eight weeks.
Prozac, a widely used antidepressant, usually starts to improve sleep, energy, or appetite within one to two weeks, but full improvement in mood may take up to eight weeks. This timeline can vary based on factors such as dosage and individual metabolism, so regular communication with your healthcare provider is important to optimize your treatment.
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Prozac 101: Essential Information
The FDA approves Prozac for the treatment and management of the following:
Most adults (people 18 and older) can take Prozac for depression, OCD, and bulimia. However, children and adolescents 8 and older can safely take it for MDD.
Furthermore, Prozac is also used as a combinational treatment (treatment that combines two or more therapeutic agents) with Zyprexa (olanzapine) for the following:
Off-Label Uses
Prozac is sometimes prescribed off-label, meaning it’s used for conditions not specifically approved by the FDA, to treat:
- Attention-deficit disorder (ADD), a condition marked by hyperactivity and impulsivity that affects a person’s day-to-day life.
- Borderline personality disorder (BPD), a mental health condition involving challenges with mood, relationships, and self-image
- Sleep disorders
- Headaches
- Mental illness
- Post-traumatic stress disorder (PTSD)
- Tourette’s syndrome (a nervous system disorder causing sudden twitches, sounds, and movements), obesity, sexual problems, and phobias(fear of things, objects, or places).
How Does Prozac Work?
Prozac is part of a group of drugs known as SSRIs (selective serotonin reuptake inhibitors). It works by preventing the reabsorption of serotonin, a brain chemical, and boosting its levels.
The high serotonin levels carry signals between neurons, providing the sensation of happiness and reducing depression disorder.
As mentioned above, Prozac comes with an FDA boxed warning about an increased risk of suicide in people with MDD. Young adults, teenagers, and children may experience worsening depression and may be more likely to become suicidal.
Close monitoring and emotional help can ease the symptoms in these people to avoid any harm.
Timeline for Prozac’s Effects
You might notice some improvements in sleep, energy, or appetite within one to two weeks of starting Prozac. However, it can take up to six to eight weeks for mood and interest in daily activities to fully improve.
Prozac may take four to five weeks or longer to fully improve symptoms or reach its full effect.
Keep in mind, the time it takes for Prozac to work can vary based on different factors affecting each individual.
Factors that may affect Prozac’s effectiveness include:
- Dosing Volume: Relief can be delayed if the dose is too low, while a high dose may cause side effects like nausea or dizziness
- Weight: Individuals with higher body weight might experience delayed effects compared to those with average weight
- Metabolism: A slower metabolism can delay the drug’s effects, as it processes differently in each body
Continue to take Prozac even if you feel well. Do not stop taking it without talking to your healthcare provider. Sudden discontinuation of Prozac may cause withdrawal symptoms.
How Effective Is Prozac?
SSRIs, like Prozac, are effective in treating depression symptoms. Studies suggest they often work better than other antidepressants and placebos for people with severe depression.
In one study, over half of the participants aged 16 to 65, taking 20 milligrams of Prozac daily for eight weeks, showed symptom improvement within two weeks.
Furthermore, the cumulative response to Prozac in people of different ages at four and six weeks was 80.2% and 89.5%, respectively.
Available data indicates that improvement from Prozac treatment predominantly occurs within the first two weeks.
More research needs to be done on the exact time-to-effect and risks of Prozac, but current evidence suggests it is an appropriate first-line treatment option.
Safe and Effective Prozac Dosage
Take Prozac exactly as prescribed by your healthcare provider. Do not take it for the conditions other than prescribed.
Prozac is available in the following forms of administration:
- Capsules: 10 mg, 20 mg, or 40 mg IR (immediate release)
- Weekly capsules: 90 mg DR (delayed-release)
For context, know that the delayed-release formulation (90 mg once weekly) is similar to receiving the 20 mg daily variation of Prozac.
Here is a general overview of Prozac dosing for adults and children:
| Use: | Adult Dose: | Pediatric Dose: |
| Adult/Adolescent MDD | 20 mg/day in the morning (initial dose) | 10 to 20 mg/day (initial dose) |
| OCD | 20 mg/day in the morning (initial dose) | 10 mg/day in am (initial dose) |
| Bulimia Nervosa | 60 mg/day in the morning | N/A |
| Panic Disorder | 10 mg/day (initial dose) | N/A |
| Depressive Episodes Associated with Bipolar I Disorder | Oral in combination with Zyprexa: 5 mg of oral Zyprexa and 20 mg of Prozac once daily (initial dose) | Oral in combination with Zyprexa: 2.5 mg of oral Zyprexa and 20 mg of Prozac once daily (initial dose) |
| Treatment-Resistant Depression | Oral in combination with Zyprexa: 5 mg of oral Zyprexa and 20 mg of Prozac once daily (initial dose) | N/A |
The frequency and the dose amount should be reduced when used in people with hepatic impairment (liver problems), older adults, and people with concurrent disease or on multiple concomitant medications.
Your healthcare provider will determine the most suitable dose for you.
Prozac Side Effects: What Should You Expect?
Prozac is effective when taken as prescribed. Like other SSRIs, it can have common, mild, and rare yet severe side effects.
Therefore, closely monitor yourself or a loved one for the potential emergence of any adverse effects.
If you notice that these or other side effects begin to worsen or do not dissipate, contact your healthcare provider immediately.
Finally, per its boxed warning, be acutely aware of the emergence of suicidal thoughts or tendencies.
Common Side Effects
Common side effects of Prozac, which often improve in a week or two, include:
However, as a byproduct of using Prozac, sexual side effects, such as problems with orgasm, decreased sex drive or ejaculatory delay, and inability to get or keep an erection, often do not diminish over time.
Severe Side Effects
More rare but severe side effects associated with the use of Prozac include:
- Allergic reactions include symptoms such as rash, urticaria (hives), blisters, itching, swelling of the face, throat, tongue, lips, eyes, hands, feet, ankles, or lower legs, and difficulty breathing or swallowing
- Fever
- Joint pain
- Severe muscle stiffness or twitching
- Hallucinations
- Cardiac arrhythmia (abnormal heart rhythm)
- Fainting
- Seizures
- Abnormal bleeding or bruising
Be aware that Prozac might decrease appetite and lead to weight loss in children. It’s important to monitor growth carefully and discuss any risks with your child’s healthcare provider.
Call your healthcare provider right away if anyone taking Prozac experiences any of the following symptoms:
- New or worsening depression
- Thinking, planning, or trying to harm oneself
- Extreme worry
- Panic attacks
- Difficulty falling asleep or staying asleep
- Irritability
- Abnormal excitement or doing things haphazardly without thinking
Call for medical help, and don’t wait for these symptoms to disappear or manage yourself.
Who Should Avoid Prozac?
Do not take Prozac:
Generally, you should wait at least 14 days after stopping an MAO inhibitor before you take Prozac. Also, wait at least five weeks after stopping Prozac before you can take thioridazine or an MAOI.
To make sure Prozac is safe for you, tell your healthcare provider if you have ever had:
Potential for Interaction
Prozac may cause drug-drug interaction with other drugs.
Be careful while using the following drugs when taking Prozac:
- MAOIs, such as Marplan (isocarboxazid) or Zyvox (linezolid)
- Medications for anxiety disorders, such as Xanax (alprazolam)
- Antibiotics, such as Zymaxid (gatifloxacin) or Avelox (moxifloxacin)
- Amphetamines, such as Adderall (amphetamine/dextroamphetamine) or Dexedrine (dextroamphetamine)
- Anticoagulants (blood thinners), such as Jantoven (warfarin)
- Antidepressants (mood elevators), such as Norpramin (desipramine), or Pamelor (nortriptyline)
- Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs), such as Advil (ibuprofen) and Aleve (naproxen).
- Insulin or oral medications for diabetes, such as Amaryl (glimepiride) or Glucotrol XL (glipizide)
- Medications for Parkinson’s disease, such as Zelapar (selegiline) or Azilect (rasagiline)
- Medications for mental illness, such as Clozaril (clozapine)
- Medications for migraine headaches, such as Relpax (eletriptan) or Maxalt (rizatriptan)
- Medications for seizures such as Tegretol (carbamazepine) or Dilantin (phenytoin)
- Other SSRIs, such as Celexa (citalopram) or Paxil (paroxetine)
- Serotonin-norepinephrine reuptake inhibitors (SNRI) medications, such as Pristiq (desvenlafaxine) or Cymbalta (duloxetine)
Tell your healthcare provider about all your over-the-counter (OTC) or prescription medicines.
Your healthcare provider may need to change the doses of your medications or monitor you carefully for side effects.
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