Finasteride Side Effects: Everything You Need To Know Before Using The Hair Loss Treatment

Scott McDougallMPharmGPhC 2079324Director & Registered Manager

Reviewed on 4 Jul 2023

If you suffer from pattern hair loss or male pattern baldness, then you’ve probably heard of the hair loss treatment Finasteride, which is the active ingredient in Propecia. This prescription drug is extremely effective at tackling hair loss and even promoting hair regrowth, and Finasteride side effects are generally uncommon.

Although the risk of experiencing these adverse effects is low, it’s important to be aware of how this therapy could potentially affect patients like you and how likely you are to experience any common Propecia side effects.

On this page, we’ll be talking about the common side effects of Finasteride in detail so that you know exactly what to expect if you decide to use this treatment.

How Propecia Works

Propecia contains the active drug finasteride, which belongs to a drug class of medications called 5-alpha-reductase inhibitors. Finasteride works by blocking the enzyme 5-alpha-reductase, which decreases the conversion of testosterone into dihydrotestosterone (DHT).

DHT contributes to male pattern baldness in those with a genetic sensitivity. It binds to receptors in hair follicles on the scalp, causing them to shrink and lose the ability to grow thick hair.

Propecia stops further hair loss by decreasing DHT in the scalp and allows the regrowth of stronger, thicker hairs. Clinical studies have shown Propecia effectively slows hair loss in over 80% of men.

Finasteride Side Effects

Everyone’s body is unique, and medication reactions can vary from person to person. Some users of Propecia will not experience any side effects at all and will have an extremely positive experience with the medication. You can go to our Finasteride reviews page to find out how real users got on with Finasteride.

However, there are some possible side effects that you may experience if you decide to use Finasteride for hair loss. Some people may experience the most common or more unusual side effects of using this treatment.

Here are some of the known side effects of Finasteride:

Common side effects (may affect up to 1 in 10 people)

impotence (not able to achieve or maintain an erection), that may continue after stopping the medication
decreased libido (less desire to have sex)
changes or problems with ejaculation such as a decrease in the amount of semen released during sex

Uncommon frequency (affects between 1 and 10 people of every 1000)

Loss of libido
Depression or lowering of mood
Erectile dysfunction — difficulty in achieving or maintaining an erection
Ejaculation disorders – such as problems ejaculating or reduced volume of ejaculate

Unknown frequency

Hypersensitivity reactions — such as hives, itching, skin rash, or swelling of the face and lips
Heart palpitations
Tender or swollen breasts
Testicular pain

The frequency of the above effects from Finasteride (listed under ‘unknown frequency’) is not currently known as insufficient data is available from clinical trials and studies. That said, these potential side effects are thought to be very uncommon and rarely occur.

The likelihood of experiencing Finasteride's above side effects may vary from user to user; what one individual may encounter could be completely different from another.

But keep in mind that if you notice any nipple discharge, lumps, and other changes in breast tissue, get in touch with a health care professional immediately, as it could be a sign of a more prominent issue like breast cancer.

If you have been taking Propecia and you are concerned about any reactions or unwanted effects you are experiencing (particularly if you experience persistent side effects that feel severe or painful), then you should seek out medical attention and consult your healthcare provider for further guidance.

Sexual Health Side Effects

Finasteride has been known to produce side effects on the sexual function of the men taking it. Finasteride can potentially cause decreased libido, impotence, sexual dysfunction and ejaculation problems.

We recognise the concerns many have about sexual side effects. While these effects are uncommon, affecting between 1 and 10 people out of every 1000 users (less than 1%), informing and monitoring any changes is essential.

Most of the time, these sexual side effects will appear within the first year of using Finasteride — but if you are concerned at all, you should speak to a healthcare professional who can provide medical advice.

Finasteride and Blood Pressure

Finasteride may cause your blood pressure to drop when you sit up or stand after lying down. This can cause dizziness, and in some cases, fainting. The risk of this side effect is higher if you take finasteride with an alpha blocker, another medication used to treat BPH.

How To Reduce Side Effects

While finasteride can cause side effects, there are steps you can take to reduce your risk:

Follow the Prescribed Dose
Take only the recommended dose to avoid increasing your risk of side effects.
Avoid Double Doses
Take finasteride at the same time daily. If you miss a dose by more than 6 hours, skip it—don’t double up.
Consult Your Doctor for Adjustments
If side effects occur, speak to your doctor. They may adjust your dosage or suggest an alternative.
Disclose Any Health Issues
Let your doctor know if you have liver problems, as finasteride is processed by the liver.
Explore Alternatives
If side effects are a concern, consider alternatives like minoxidil, laser therapy, or topical finasteride (though not FDA-approved).

Inform Your Doctor About Other Medications
Always tell your doctor about other drugs or supplements you're taking, especially alpha blockers or natural DHT blockers, as they can increase side effect risks when combined with finasteride.

Finasteride and Memory Loss

In some very rare circumstances, Finasteride has been linked to neurological side effects, such as memory loss.

This tends to be part of a wider problem known as post finasteride syndrome (PFS), which is experienced by a very small percentage of men who take Finasteride.

PFS is made up of a range of persistent sexual, physical, neurological and mental adverse reactions — including memory loss and other cognitive difficulties.

We understand the worries surrounding memory loss. While it’s extremely rare, it’s crucial to be aware and seek support if you notice any changes.

Finasteride and Prostate Cancer

Initial studies suggested that there was a link between Finasteride and an increase in prostate cancer risk. Since then, however, further research has been carried out that has disproved this theory.

In fact, Finasteride has been found to significantly reduce the risk of prostate cancer and may even prevent it. Follow-ups in trials were carried out over nearly 20 years and established Finasteride as an extremely safe and effective medication to use.

Finasteride and Depression

There is a potential connection between Finasteride and depression; some users have reported an increase in mental health issues such as depression, anxiety, or panic attacks.

At The Independent Pharmacy, we know that mental well-being is paramount. While most men respond well to Finasteride, if you ever feel it’s impacting your mental health, please prioritise your well-being and seek guidance from a healthcare provider.

If you have any existing mental health problems, it is not recommended for you to take Finasteride 1mg tablets which are available under the name of Propecia to treat hair loss - Minoxidil topical solution may be more appropriate for you.

Finasteride Shedding

Some users of Finasteride may experience an increased shedding of hair during the first three months of treatment (or sometimes earlier, in the first month of use), which means that you could notice a decrease in hair count. This initial shedding can last for a few months. This is a normal part of the hair cycle where thinner hairs make way for newer, thicker hairs in the follicle. You should notice that you have an increase in hair growth and regrowth between 6 to 12 months after starting Finasteride.

If you are concerned about excess shedding, you can seek advice from a medical professional.

Finasteride and Pregnancy

We want to emphasise the importance of safety. While Finasteride is designed for men with male pattern baldness, it’s not suitable for women - especially those who are or may become pregnant. This is because Finasteride could interact negatively with female hormones.

As a precaution, women are even warned not to handle Finasteride tablets, particularly if they are crushed or broken, to avoid absorption into the body. This is particularly important for pregnant women (or women who may become pregnant) because of the possibility of Finasteride absorption, which may be harmful to a male foetus. However, there are currently no adverse pregnancy outcomes in mothers exposed to Finasteride.

If you are a man taking Finasteride, and you and your partner wish to try to get pregnant, it would not be advisable as Finasteride can be present in the sperm. As such, it is always advisable to use a condom during sex whilst taking Finasteride and if you are thinking of trying for a baby, to discuss it with your doctor before you start. If you are concerned or have any questions, you can speak to your healthcare team to confirm.

Allergic Reactions to Propecia

In rare cases, individuals may experience hypersensitivity reactions to the active drug finasteride or other ingredients in Propecia tablets. Seek prompt medical care if you develop any symptoms of a serious allergic reaction, such as:

Hives, itching skin, or rash
Swelling of the face, lips, tongue, or throat
Wheezing or difficulty breathing
Feeling faint, dizzy, or lightheaded
Chest tightness or pain
Rapid heart rate or palpitations

Drug Interactions

There are no known drug interactions between finasteride and other medications. However, be sure to inform your doctor of any prescription, over-the-counter, herbal, or dietary supplements you are taking.

Propecia should not be used along with other similar medications like dutasteride or saw palmetto, as this increases the risk of side effects.

Long-Term Effects of Propecia

Propecia works only as long as you continue taking it daily. When you stop taking Propecia, DHT levels rise again and hair loss resumes.

There is no evidence from clinical trials and studies that Propecia has any long-term effects on fertility or sexual function after discontinuation. Most side effects resolve soon after stopping treatment.

However, in rare cases, some men develop persistent sexual, physical, and psychological side effects after quitting Propecia, known as a post-finasteride syndrome (PFS).

PFS appears to be very uncommon, but research into its causes and treatments is limited. Discuss the risks and benefits thoroughly with your licensed healthcare professional before starting Propecia. Monitor for any lasting changes while on treatment.

What Happens After You Stop Using Finasteride?

Finasteride works by stopping your body from converting testosterone to dihydrotestosterone (DHT). DHT is the hormone responsible for male pattern baldness, so stopping the conversion of testosterone will halt hair loss and can even promote hair growth.

Unfortunately, Finasteride isn’t a cure for hair loss, but an ongoing treatment and therapy. Although Finasteride is an effective hair loss medication, it only works while you are taking it.

This is because Finasteride only has a half-life of around five to six hours — which means that you will need to take a tablet daily to keep the levels of Finasteride in your body topped up.

If you stop using Finasteride, your body will begin to convert testosterone to dihydrotestosterone (DHT) again, and your hair loss may continue.

Is Finasteride Safe?

Clinical research has shown that Finasteride is an effective hair loss treatment that is safe to use and has few side effects (which are uncommon).

We understand the importance of safety. For most individuals, Finasteride is safe and offers positive benefits. However, in very rare circumstances, Finasteride (and other finasteride-based medications) can result in post-finasteride syndrome (or PFS).

PFS causes a complex set of symptoms; sufferers will experience a range of persistent sexual, physical, neurological and mental adverse reactions. For more information about PFS, you can read our post-finasteride syndrome page.

It is extremely rare to suffer from this condition, and the vast majority of Finasteride users will only experience very mild side effects, if any at all.

If you are unsure about taking Finasteride, you can speak to a healthcare professional who will be able to advise.

The Difference in Finasteride Dosage

Finasteride is sometimes available in two different doses: 1mg and 5mg, but what does that mean to you?

You might think that a 5mg dose of Finasteride would be a stronger, more effective way of treating hair loss, but it’s actually used for a completely different condition; Finasteride’s other medical use is to reduce the symptoms of an enlarged prostate gland or prostatic hyperplasia.

The dosage of Finasteride for prostate treatment is higher than the dosage used for hair loss: 5mg is prescribed to men with an enlarged prostate.

Finasteride 5mg should not be used to prevent hair loss as it is no more effective than Finasteride 1mg tablets but has a higher risk of side effects.

The Independent Pharmacy only provides Finasteride 1mg tablets for treating hair loss and male pattern baldness; we do not currently offer Finasteride 5mg for treating enlarged prostate glands. For more information, please go to our Finasteride dosage page.

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