Dutasteride vs. Finasteride: What’s the Difference?
Aging is associated with an increased risk of experiencing many health conditions. Two of the most common conditions associated with aging in men are benign prostatic hyperplasia (BPH) and male pattern baldness. Both conditions result from changing levels in an androgen hormone called dihydrotestosterone (DHT), which often increases as men age.
Benign prostatic hyperplasia is associated with uncomfortable urinary symptoms that can be uncomfortable and embarrassing and typically worsen with age. Unfortunately, the condition is very common, with approximately 50 percent of men between the ages of 51 and 60 experiencing the condition, and up to 90 percent of men older than 80 affected.
Dutasteride and finasteride are two popular generic prescription medications that are used to treat benign prostatic hyperplasia. The two medications have similar names, purposes, and side effects, so when it comes to dutasteride vs. finasteride, what’s the difference?
Dutasteride is a generic prescription drug that is also sold under the brand name Avodart. Dutasteride is a dual 5α-reductase inhibitor (5-ARI) characterized by the inhibition of both isozymes of 5α-reductase. The medication is commonly prescribed by healthcare professionals at a baseline dose of 0.5 mg and is taken by mouth once per day.
Finasteride is a generic prescription medication that is sold under the brand name Proscar. This drug is prescribed at a dose of 5 mg per day or 1 mg per day, depending on which condition is being treated.
Dutasteride and finasteride are both prescribed for the treatment of benign prostatic hyperplasia, also known as enlarged prostate, in adult men. Finasteride is also approved by the U.S. Food and Drug Administration (FDA) for the treatment of androgenetic alopecia, i.e. male pattern hair loss. Dutasteride is not FDA-approved for the treatment of male pattern baldness, but some doctors prescribe the medication for this purpose off-label.
Benign prostatic hyperplasia
Benign prostatic hyperplasia, or enlarged prostate gland, is a common medical condition that is more likely to occur as men age. The condition typically occurs on a spectrum, and symptoms can range in severity from mild to severe. Most patients find that their symptoms get worse as they age.
While it may be logical to think that a more enlarged prostate volume corresponds to more severe symptoms, especially in urology, this is not the case. Patients with relatively minor enlargement of the prostate may experience severe symptoms, while those with significant enlargement may experience only minor or short-term symptoms.
Symptoms of benign prostatic hyperplasia include:
- Urinary tract symptoms like the urgent need to urinate and weak urine stream
- Nighttime urination (nocturia)
- Difficulty starting to urinate and urinary retention
- Frequent need to urinate
- Urine stream that stops and starts
- Inability to empty the bladder completely
- Dribbling following urination
Male pattern baldness
An estimated 50 million adult men in the United States are predisposed to male pattern baldness, a hereditary hair loss condition that tends to get worse with age. Male pattern baldness is most commonly associated with hair loss that causes a receding hairline and thinning on the crown of the head.
Hair loss in men with a genetic predisposition to male pattern baldness is caused by increased levels of a hormone called DHT, which shrinks the hair follicles in the scalp. As the hair follicles shrink, existing hair falls out and new hair growth is prevented, so hair count decreases overall.
DHT is the same hormone that causes benign prostatic hyperplasia, which is why there is some overlap in medications that treat the conditions. Drugs should only be taken to treat male pattern baldness under professional medical advice.
Drug Class and Treatment Mechanisms
Dutasteride and finasteride both belong to a class of drugs called 5-alpha reductase inhibitors. Drugs in this class of medication inhibit the action of the 5-alpha reductase enzyme, which is used by the body to convert free testosterone in the body into a substance called DHT. Rising levels of DHT are more likely to occur as men age, and the increase in levels of the hormone causes the enlargement of the prostate and hair loss in men who are genetically predisposed to male pattern baldness.
Both dutasteride and finasteride work by inhibiting the action of the 5-alpha reductase enzyme, which prevents the conversion of testosterone to DHT and keeps DHT levels in the body low. Finasteride works by selectively inhibiting the Type 2 isoenzyme of 5-alpha reductase, while dutasteride inhibits both Type 1 and Type 2 isoenzymes of 5-alpha reductase.
Patients using dutasteride and finasteride will find that their prostates will return to a more normal size for as long as the medication is used, thereby diminishing urinary symptoms associated with the condition. Similarly, finasteride will prevent hair loss and encourage hair regrowth in men with male pattern baldness for the duration of its use.
Comparison of Effectiveness
Clinical trials conducted on the effectiveness of dutasteride vs. finasteride have found that dutasteride significantly reduces the amount of serum DHT in the body compared to finasteride. One study found that dutasteride reduced the amount of serum DHT in the body by approximately 90 percent, while finasteride reduces the amount of serum DHT by approximately 70 percent. It is believed that the suppression of the Type 1 isoenzyme of 5-alpha reductase in addition to the Type 2 isoenzyme accounts for the difference in effectiveness between finasteride and dutasteride.
Another study confirmed the findings of the aforementioned study and noted that there did not appear to be a clinically significant difference in the adverse event profiles associated with dutasteride and finasteride, as well as between the dutasteride group and placebo group. Put more simply, that means that both medications (and the placebo group) were found to cause a similar incidence of side effects in study participants.
Both medications take approximately six months before patients achieve an improvement in the symptoms of their benign prostatic hyperplasia.
Finasteride and dutasteride are both generally well tolerated by patients who use the drugs for the treatment of benign prostatic hyperplasia or male pattern baldness. The medications belong to the same drug class and work very similarly, so there is a significant overlap in the side effects caused by each drug.
Studies show that the drugs have a similar incidence of side effects. However, like all medications, they are associated with the risk of certain side effects. Both medications can cause sexual side effects like reduction in arousal or desire, particularly when first starting use of the medications. Regardless of whether a patient is taking dutasteride or finasteride, side effects are most likely to occur at the beginning of treatment and disappear or diminish over the course of several days or weeks.
The safety of dutasteride and finasteride depend on the individual's response to the drug. If you find yourself experiencing long-term side effects from the drug, schedule a follow-up appointment with your healthcare provider.
Finasteride is taken at a lower dose of 1 mg per day when used for the treatment of male pattern baldness and a higher dose of 5 mg per day when used for the treatment of benign prostatic hyperplasia. Correspondingly, the higher dose of the medication is associated with an increased incidence of side effects. Dutasteride is prescribed at a 0.5 mg dose for the treatment of benign prostatic hyperplasia and is sometimes prescribed off label for male pattern baldness.
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Mild side effects associated with finasteride and dutasteride include:
- Trouble getting or keeping an erection (erectile dysfunction)
- Decreased sex drive (sexual dysfunction)
- Sexual side effects such as ejaculation disorder or reduced ejaculate
- Breast enlargement and breast tenderness to the touch
- Skin rash
While most of the side effects caused by finasteride and dutasteride are mild, some patients may experience severe or potentially life threatening side effects when using the medications. These side effects are very rare, but have been documented to occur.
Patients experiencing any of the following side effects should contact a doctor right away and should contact 911 if their symptoms feel life threatening.
- Nipple discharge
- Lumps or pain in your breasts
- Swelling of your lips, tongue, throat, or face
Dutasteride and finasteride can also increase a patient’s risk of experiencing certain types of prostate cancer and can cause a faster rate of growth in existing tumors. Patients who have a history of prostate cancer or who are currently diagnosed with prostate cancer should not use finasteride or dutasteride.
Finasteride and dutasteride are both effective prescription treatments for benign prostatic hyperplasia. Finasteride is also the only FDA-approved medication for the treatment of hair loss caused by male pattern baldness, while dutasteride is sometimes prescribed off-label for the same purpose.
Both medications are well-tolerated but can cause frustrating side effects, including sexual side effects and dysfunction in some patients. Side effects associated with either medication typically subside after use of the medication is discontinued, but may persist in rare cases. Both medications are sold by prescription only and are available in generic and brand name forms at your local pharmacy.