From the Guidelines
Dutasteride can cause several side effects, including sexual dysfunction issues such as decreased libido, erectile dysfunction, and ejaculation disorders, which affect approximately 5-10% of users, as well as breast tenderness or enlargement (gynecomastia) in about 1-2% of cases, as reported in studies such as 1.
Common Side Effects
The most common side effects of dutasteride include:
- Decreased libido
- Erectile dysfunction
- Ejaculation disorders
- Breast tenderness or enlargement (gynecomastia) These side effects are likely due to the mechanism of action of dutasteride, which inhibits the enzyme 5-alpha reductase, resulting in lower dihydrotestosterone (DHT) levels throughout the body, as discussed in 1.
Less Common Side Effects
Other potential side effects of dutasteride include:
- Dizziness
- Headache
- Skin reactions like rash or itching
- Depression
- Anxiety
- Allergic reactions These side effects are less common, but can still occur in some patients, as noted in 1 and 1.
Importance of Monitoring
Patients should report persistent or severe side effects to their healthcare provider immediately, especially allergic reactions or significant mood changes. Most side effects are reversible after discontinuation, though some may persist, highlighting the need for close monitoring and regular follow-up appointments, as emphasized in 1.
From the FDA Drug Label
The most common adverse reactions reported in subjects receiving dutasteride were impotence, decreased libido, breast disorders (including breast enlargement and tenderness), and ejaculation disorders The most common adverse reactions reported in subjects receiving combination therapy (dutasteride plus tamsulosin) were impotence, decreased libido, breast disorders (including breast enlargement and tenderness), ejaculation disorders, and dizziness Dutasteride capsules may cause serious side effects, including: Rare and serious allergic reactions, including: Swelling of your face, tongue, or throat Serious skin reactions, such as skin peeling The most common side effects of dutasteride capsules include: trouble getting or keeping an erection (impotence)* a decrease in sex drive (libido)* ejaculation problems* enlarged or painful breasts.
The side effects of Dutasteride (Avodart) include:
- Impotence
- Decreased libido
- Ejaculation disorders
- Breast disorders (including breast enlargement and tenderness)
- Dizziness (when used in combination with tamsulosin)
- Rare and serious allergic reactions (including swelling of the face, tongue, or throat)
- Serious skin reactions (such as skin peeling)
- Enlarged or painful breasts Some of these events may continue after stopping dutasteride capsules 2, 2, 2.
From the Research
Side Effects of Dutasteride (Avodart)
The side effects of dutasteride, as reported in various studies, include:
- Decreased libido 3, 4, 5, 6, 7
- Erectile dysfunction 3, 4, 5, 6, 7
- Ejaculation disorders 3, 4, 5
- Gynecomastia 3, 4, 5, 7
Comparison of Side Effects with Placebo
Studies have shown that these sexual adverse events are only modestly elevated when dutasteride treatment is compared with placebo 3.
Long-term Use and Side Effects
Long-term use of dutasteride over 4 years did not increase side effects 3, 5.
Combination Therapy and Side Effects
The combination of dutasteride and tamsulosin is well-tolerated, with an adverse event profile consistent with those reported for both monotherapies 6.