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What Factors Affect Fluoxetine Dosages?

Tricia Christensen
Tricia Christensen
Tricia Christensen
Tricia Christensen

Fluoxetine dosages are determined by age, the condition being treated, and the type of formulation of the drug. They are also impacted by patient response, as this is the most reliable means of determining drug and dose efficacy. Patients might take other medications that may impact response or directly influence the way fluoxetine, often sold under the name Prozac®, works and is metabolized by the body. In these cases, dosages could require adjustment.

The first consideration is the age of the patient, and usually the drug is not given to children under the age of seven. Children over seven through their mid-teens could receive fluoxetine dosages that vary from 10 to 60 mg for conditions like major depression, obsessive-compulsive disorder (OCD) or bulimia nervosa. Younger children generally receive lower doses, but the condition is also a strong influence. OCD dosage can climb to 60 mg in the under-18 population, but dosages for depression in children usually don't exceed 20 mg. Like many antidepressants, fluoxetine usually begins with a lower dose and is increased over a few weeks to a maintenance dose.

Age also impacts dosage amount in another way. If fluoxetine is used in the geriatric population, the doses are usually smaller than "adult" doses. Recommendations for this population may more closely resemble recommendations for children.

Fluoxetine capsules can be used to treat panic disorders in adults.
Fluoxetine capsules can be used to treat panic disorders in adults.

Adults with a variety of conditions take fluoxetine dosages that are partly based on the condition and on their response to the drug. Initiation therapy typically begins at 20 mg, though with conditions like panic disorder, the initial recommended dose is 10 mg. In major depressive disorder, many patients respond favorably to the starting dose of 20 mg, but if this insufficient, dosages can climb to a maximum of 80 mg per day. With OCD, patients tend to have therapeutic benefits with drug levels of 20 to 60 mg, but some patients may take up to 80 mg.

Like many antidepressants, fluoxetine usually begins with a lower dose and is increased over a few weeks to a maintenance dose.
Like many antidepressants, fluoxetine usually begins with a lower dose and is increased over a few weeks to a maintenance dose.

Individuals with bulimia tend not to respond to fluoxetine dosages below 60 mg. A very different dosing schedule is recommended for women with premenstrual dysphoric disorder. They may take 20 to 60 mg for the 14 days each month prior to the onset of their periods.

Another option for dosing is available with a pill known as "weekly Prozac®." This drug may be appropriate for people who have stabilized conditions that don't appear to require daily treatment. It is taken once a week, usually in 20 mg amounts.

Certain medications used in combination with fluoxetine may impact the way the body reacts to or clears the drug. One of these is olanzapine, an atypical antipsychotic, which is sometimes prescribed with fluoxetine to address treatment resistant depression in major depressive disorder and bipolar disorder. The wisdom of using fluoxetine in bipolar is questionable given its potential to induce manic and hypomanic states, but the practice is not unknown. The therapeutic range for is 25 to 50 mg when olanzapine is used, and the two drugs are available in a combination pill.

Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent WiseGEEK contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

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Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent WiseGEEK contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

Learn more...

Discussion Comments

bythewell

@Ana1234 - I actually like that fluoxetine takes so long to enter and leave the system properly. It makes me feel like I can accidentally forget to take my dose for a few hours without it becoming a catastrophe.

I have noticed that the very few times that I've forgotten for almost a day to take the fluoxetine, the side effects increased a little bit, like slight headaches and nausea, but it didn't seem to do much to my mood.

Ana1234

@browncoat - Unfortunately, we still don't know very much about why the brain reacts to a lot of these drugs the way it does, particularly on an individual level. Doctors know that if they give people with particular symptoms a particular drug they are likely to get a positive reaction, but they can't pinpoint exactly what will work until they try it. And changes in fluoxetine dosages can take weeks to come into effect.

So it can be a very long, frustrating process. And unfortunately, some people give up. But I hope your sister found something that worked for her.

browncoat

My sister has bipolar disorder and it took a long time for her to be properly diagnosed. I remember they tried putting her on this kind of medication at one point and it seemed to make her happier, but also completely took away her ability to calm down.

The doctor told us after she was properly diagnosed that it was likely that it was only treating her depression and not the mania side of the bi-polar which makes sense.

In some people that might even work, depending on how bad their mania is, but it definitely did not work with my sister. I guess you've just got to keep trying until you figure out the best medications and dosages for each patient.

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    • Fluoxetine capsules can be used to treat panic disorders in adults.
      By: David Stuart
      Fluoxetine capsules can be used to treat panic disorders in adults.
    • Like many antidepressants, fluoxetine usually begins with a lower dose and is increased over a few weeks to a maintenance dose.
      By: Alliance
      Like many antidepressants, fluoxetine usually begins with a lower dose and is increased over a few weeks to a maintenance dose.