Dutasteride works in a similar way to finasteride by reducing levels of dihydrotestosterone (DHT), the hormone that drives male pattern baldness. While primarily licensed for prostate conditions, it's increasingly prescribed off-label for hair loss. Most men tolerate it well, but like any medication, dutasteride can cause side effects in some users.
Knowing the potential benefits and risks helps set realistic expectations before starting treatment. Here's what the current research and UK guidance show.
Key Takeaways
- Dutasteride works similarly to finasteride by blocking DHT production, and it is used off-label for hair loss in men
- Dutasteride and finasteride have similar side effect profiles
- Most side effects are mild, temporary, and resolve either during continued treatment or within weeks to months of stopping.
- Serious reactions are rare, but mood changes, allergic symptoms, or new breast lumps require prompt medical review
Common dutasteride side effects
Like all medicines, dutasteride can cause side effects, though not everyone will experience them. If side effects do occur, the most common are:
- Erectile dysfunction (problems getting or keeping an erection)
- Reduced sex drive
- Ejaculatory changes (such as reduced semen volume)
- Breast tissue changes (tenderness, swelling, or enlargement)
Topical dutasteride (applied directly to the scalp) may cause fewer whole-body side effects than oral tablets, though more research is needed to confirm this.
How common are these side effects?
The good news is that these side effects only affected a small number of men in clinical trials.
Erectile dysfunction occurred in 6% of men during the first year, but this dropped to just 1.7% by year two. Reduced libido followed a similar pattern, affecting 3.7% of men initially before falling to 0.6% in the second year. Breast changes occurred in about 1.3% of men and remained stable.
What's encouraging is that most side effects resolved on their own while men continued taking the medication.
Serious and rare side effects of dutasteride
While most side effects are mild, there are some more serious side effects to be aware of.
Get immediate medical help if you experience:
- Signs of an allergic reaction, such as swelling of your face, lips, tongue or throat, difficulty breathing, or a severe skin rash
Contact your doctor promptly if you notice:
- Changes in your breast tissue, including lumps, pain, or any discharge from your nipples. While very rare, cases of male breast cancer have been reported in men taking dutasteride
- Feeling persistently down or experiencing symptoms of depression
- Pain or swelling in your testicles
In rare cases, dutasteride can cause people to lose hair, or to develop more hair on their body.
Does dutasteride increase the risk of heart failure?
You may have read about heart failure being associated with dutasteride. Here's what the research shows:
In clinical trials involving older men (50-75 years) taking dutasteride for prostate conditions, there was a small increase in heart failure reports (0.7% vs 0.4% on placebo). This risk appeared higher when dutasteride was combined with another prostate medication called an alpha-blocker (1.0%).
However, when researchers looked at the bigger picture, analysing 12 studies with nearly 19,000 men, they didn't find a clear increased risk of heart failure, heart attacks, or strokes from dutasteride.
What this means for you:
If you're a younger man (younger than 50) taking dutasteride for hair loss (not prostate issues), and you're not taking other medications alongside it, this isn't likely to be a concern. That said, if you have a history of heart problems, it's worth having a conversation with your doctor before starting treatment.
If you ever experience symptoms like shortness of breath, extreme tiredness, or swollen ankles and legs, contact your doctor right away.
Are dutasteride side effects permanent?
No, most side effects are temporary. Studies show that sexual side effects, such as erectile dysfunction or ejaculatory changes, typically resolve over time. As we mentioned earlier, these side effects become less common the longer you take the medication—many men found their symptoms improved within the first few months.
If you decide to stop taking dutasteride, any side effects you've experienced will usually resolve within a few weeks to months.
Side effects: Dutasteride vs finasteride
Finasteride is another medicine that can be used to treat hair loss in men, and it works in a similar way to dutasteride by blocking DHT production. Because they work through the same mechanism, their side effects are very similar.
The most common side effects include:
- Erectile dysfunction (difficulty getting or maintaining an erection)
- Reduced libido (low sex drive)
- Ejaculatory changes (for example, reduced semen volume during sex)
Finasteride can also cause breast tissue changes (tenderness or swelling) and low mood, though these occur less frequently.
Side effects: Topical dutasteride vs oral dutasteride
Topical dutasteride is applied directly to the scalp and is still being researched. Early studies suggest it may cause fewer systemic (whole-body) side effects than oral tablets because less of the medication enters your bloodstream.
In clinical trials, topical dutasteride has been well-tolerated with no serious adverse events reported. The most common side effects observed were mild skin changes at the application site, including:
- Glazed appearance of the skin
- Mild peeling or flaking
These skin effects were generally minor and didn't cause participants to stop treatment.
At Manual, we currently offer oral capsules that combine dutasteride with minoxidil. We do not offer topical dutasteride at this time while we continue to assess the evidence.
Side effects: Dutasteride with minoxidil
If you take dutasteride for hair loss, you might also use minoxidil, another effective hair loss treatment.
The most important thing to know is that minoxidil commonly causes increased hair shedding during the first few weeks of treatment. While this can be alarming, it's actually a sign that the medication is working—old hairs are being pushed out to make way for new growth.
Like dutasteride, minoxidil can cause you to grow more hair on your body, and taking it as a topical solution can irritate your scalp. Minoxidil can also cause headaches, low blood pressure, dizziness, and ankle or leg swelling. The good news is that most people who experience side effects are able to continue treatment, often with an adjusted dosage.
Taking minoxidil with dutasteride shouldn't make the side effects of either medicine worse, as the two medications don't interact with each other.
How to manage the side effects of dutasteride
As we mentioned earlier, side effects decrease significantly after the first few months of treatment, and most resolve completely either during continued use or after stopping.
However, if side effects are affecting your confidence, relationships, or quality of life, don't hesitate to speak with your healthcare provider. They’ll be able to talk to you about your options, including changing your dose, switching to a different treatment, or stopping treatment altogether.
You should always get immediate medical attention for serious side effects, such as allergic reactions or symptoms of depression.
Your hair loss journey
Although dutasteride can cause side effects, these are usually manageable.
At Manual, our clinicians make sure you get the best treatment possible. They closely monitor your progress, adjust your plan based on your needs and goals, and provide free, convenient support via video calls and WhatsApp. Take the hair loss quiz to see if our treatment plan could be a good fit for you.
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