Dutasteride half-life may be a concern if you’re using it as a hair loss treatment. 80% of men experience male pattern baldness by the age of 80 [1], so it’s no surprise that interest in medications to treat this condition continues to grow. Dutasteride is not licensed as a hair loss treatment in the UK, partly due to concerns surrounding its half-life, but many people still use it off-label.
In this article, we’ll explore:
Dutasteride is available on prescription in the UK as a treatment for benign prostatic hyperplasia (BPH), an enlarged prostate. It works by stopping the action of an enzyme (5-alpha-reductase) that converts testosterone into dihydrotestosterone (DHT). DHT stimulates prostate growth and contributes to male pattern baldness, so blocking it has the opposite effect.
Dutasteride has been shown to improve symptoms of male androgenetic alopecia (pattern baldness) [2]. It is not licensed for this purpose in the UK due to concerns about its side effects and long half-life [3]. However, several studies have shown Dutasteride to be better than Finasteride at treating male pattern baldness, with comparable side effects [2]. This suggests it may be on its way to becoming licensed in the near future.
Dutasteride is unsuitable for women and should never be used or handled by pregnant women or women who are trying to conceive [4]. It has been shown to cause congenital disabilities in male children. Handling Dutasteride puts pregnant women at risk of coming into contact with a broken capsule because contents can enter the bloodstream through the skin [4].
The term half-life is often used when discussing medications, but many people don’t know what it means. In simple terms, a drug’s half-life is how long it takes to reduce to half of its starting dose in the body.
If a drug is taken orally, like Dutasteride, only part of the dose is absorbed and enters your bloodstream. This is known as the oral bioavailability and for Dutasteride, it is 60%. It also takes around 2-3 hours for your body to absorb Dutasteride, so the peak blood level of Dutasteride is reached only 2-3 hours after the pill is taken.
For an orally administered drug, the half-life is measured as the time period from the peak blood level to the blood level that is half the amount. Understanding medication half-lives helps doctors and researchers determine how often doses should be given to maintain the drug’s effectiveness.
Dutasteride has a relatively long half-life of five weeks in humans, meaning it takes at least 5-6 months to clear from your system once you stop taking it [5]. It takes around 6-12 months to restore normal structure and function to organs affected by long-term Dutasteride treatment [5].
This is much longer than Finasteride’s half-life, which is only 4.5 hours [6]. However, when it comes to Dutasteride vs. Finasteride, Dutasteride is more effective than Finasteride at suppressing DHT levels in the scalp [6].
It’s important to understand the length of time Dutasteride stays in your system for several reasons. Firstly, its long half-life means it will have more prolonged effects than a drug with a shorter half-life, such as Finasteride.
This means Dutasteride may continue to have effects for 6-12 months when you stop taking it. On the one hand, this can be positive because you could maintain benefits such as reduced hair shedding. However, if Dutasteride levels in your blood fall below the effective concentration (the level at which beneficial effects are observed), benefits will disappear, but side effects may remain.
Your body will reach a steady-state concentration of Dutasteride after around 4-5 half-lives, without any further accumulation in your body [7], which can help to ensure beneficial effects are constant. It takes Dutasteride around 5-6 months to reach its steady-state concentration [8].
On the other hand, this can be negative if you’ve stopped taking Dutasteride due to unwanted side effects. The likelihood is that these will continue to affect you for several months or even up to a year after stopping the medication. Learn more about whether Dutasteride’s side effects are permanent.
It’s also important to be aware of Dutasteride’s half-life when taking other medications — there are 121 drugs known to interact with it [9]. While you might think this won’t affect you if you start taking one of these drugs several months after stopping Dutasteride, you may be affected if it hasn’t been fully washed out of your system yet.
Your doctor can advise you on which medications are safe to take if you are taking or have recently taken Dutasteride.
Dutasteride’s half-life is around five weeks, but this can vary depending on several factors. Let’s explore these in more detail.
Your age can significantly affect the half-life of Dutasteride in your body. Older people, in particular, may have a different half-life to a healthy middle-aged adult because metabolism slows as you age. This can affect the speed at which Dutasteride is metabolised and eliminated from the body, leading to a longer half-life.
A small, single-dose study with 36 participants found that dutasteride’s half-life increased with age. Half-life was around 170 hours in men aged 20-49, around 260 hours in men aged 50-69, and around 300 hours in men over 70 [10].
A drug interaction is when one drug affects the action of another drug in the body, leading to potential side effects or changes in effectiveness. Drugs can interact with each other to affect half-lives.
One study found that ketoconazole (an antifungal drug) significantly interacts with Dutasteride by slowing its breakdown in the body [11]. This could feasibly impact Dutasteride’s half-life. Further research on drug interactions with Dutasteride is needed to identify which other medications may interact with it.
Dosage doesn’t technically affect half-life; the amount of time for a drug to half in your body will stay the same [7]. However, higher doses of Dutasteride mean longer for the drug to completely leave your body and for any effects to fade away.
While Dutasteride can be effective, it’s not yet licensed in the UK while it continues to be researched as a hair loss treatment. However, there are other options available.
Although Dutasteride is not licensed in the UK for male pattern baldness, two other medications are — topical Minoxidil and oral Finasteride.
Finasteride works in a similar way to Dutasteride but has a shorter half-life. Minoxidil is thought to increase hair growth through vasodilation, allowing more blood to flow to the scalp and providing follicles with more oxygen and nutrients [12]. Minoxidil’s half-life is 4.2 hours [13].
Platelet-rich plasma (PRP) hair treatment is a type of regenerative medicine. It involves creating a concentrated sample of platelets from your blood, which is then injected into areas of hair loss. In general, the greater the concentration of platelets in the injected plasma, the greater the hair growth and density increase you will experience [14].
Low-level laser therapy (LLLT) uses low-powered lasers to boost hair growth. Lasers are directed at areas of hair loss, stimulating hair follicle cells and increasing blood flow to the scalp.
Scalp micropigmentation (SMP) doesn’t actually improve hair growth. However, it creates the impression of greater hair density by covering thinning or balding areas with a large number of tiny, tattooed dots that create the impression of very short hair. SMP can be used all over the head to create a buzz-cut look or in small areas to disguise patchy hair loss or cover scalp scars.
A hair transplant is a permanent solution for hair loss. There are two types of hair transplant: follicular unit extraction (FUE) and follicular unit transplantation (FUT).
Both involve taking hair from areas of healthy hair growth and transplanting it to areas of hair loss. The difference is in how hair grafts are harvested — FUE involves taking individual follicular units with lots of tiny punch incisions, leaving minimal scarring. FUT involves harvesting a strip of skin containing hair follicles, which leaves a more obvious hair transplant scar at the donor site.
Whether you’re experiencing the first signs of thinning and balding or your hair shedding is more extensive, the Wimpole Clinic can help. Our experienced hair doctors can identify whether your hair loss is due to male pattern baldness or something else using a range of diagnostic trichology tests. These may include a hair pull test or blood tests for hair loss.
Our trichologists will create a tailored treatment plan to address your hair loss when you are diagnosed. You may be a candidate for a natural-looking hair transplant — experienced surgeons create such realistic results that getting a hair transplant without anyone knowing is possible. If you’re ready to find out how your hair can be restored, book a consultation at one of our clinic locations today.
Dutasteride has side effects similar to finasteride in men, with a similar frequency. Side effects of Dutasteride may include [15]:
Breast tenderness, testicular pain, and a low sperm count are less common side effects.
One study investigated the levels of DHT in the blood when using DHT as a treatment for prostate issues. Researchers found that Dutasteride reduced serum DHT levels by 84% at 2 weeks and around 90% at 1, 2, 3 and 4 months [16]. While this study focused on prostate issues, DHT is also the main hormone behind the symptoms of male pattern baldness.
Some natural ingredients may help reduce DHT levels. These include saw palmetto for hair loss, caffeine for hair loss, and rosemary oil for hair growth. However, further research is needed to better understand the effects of these substances on male pattern baldness.
Dutasteride can be taken at any time of the day. However, it works best when it is taken consistently at the same time each day.
You should not donate blood while taking dutasteride. If a pregnant woman receives a blood transfusion that contains dutasteride, it could cause birth defects [17]. Your doctor will also advise you on any medications you should avoid while taking dutasteride, as it can interact with some drugs.
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