What happens when you stop taking finasteride?

When you stop taking finasteride, hair loss usually returns. The UK leaflet says hair gained on it is likely to be lost within 9 to 12 months. Side effects are different, and nobody can promise how they will go. For some people they clear. For others they continue, or get worse after stopping. Both the UK product information and the US label say sexual side effects can continue after the last tablet.

How long does finasteride stay in your system?

The drug leaves your blood quickly. Its effect on your hormones lasts longer.

Finasteride has a half-life of 5 to 6 hours in men aged 18 to 60, and about 8 hours in men over 70. Half-life is the time it takes for the amount in your blood to fall by half.

Finasteride works by lowering DHT, a hormone your body makes from testosterone. The US label for Proscar, the 5 mg tablet, gives one measurement of how fast DHT recovers. Healthy men took it for 14 days, and their DHT was back to its level before treatment in about 2 weeks after they stopped. The labels give no such figure for the 1 mg hair-loss dose, or for anyone who took it for years.

When will my hair fall out after stopping?

Not at once. The change shows over months.

The UK prescribing information says the benefit begins to reverse by six months after stopping. By 9 to 12 months, hair is back to where it was before treatment. The US label says the effect reverses within 12 months.

In the US trials, 48 men switched to a dummy tablet after a year on finasteride. Twelve months later, the hair they had gained was gone.

After the last finasteride tablet

5 to 6 hours

Half the finasteride in your blood is goneAbout 8 hours in men over 70.

About 2 weeks

DHT is back to its level before treatmentMeasured in healthy men who took 5 mg for 14 days.

3 months

Sexual side effects still there?That is one of the 2022 criteria for PFS. The labels give no timescale for side effects to clear.

By 6 months

Hair gained on finasteride starts to be lostThe benefit begins to reverse.

9 to 12 months

Hair is back to where it was beforeThe benefit has returned to baseline, the UK product information says.

Do finasteride side effects go away after stopping?

For some people they do, and for some they do not. In the trials of the 1 mg dose, sexual side effects cleared in the men who stopped because of them, and in most of those who kept taking it. That is not a promise for you. Trials follow people for a short time, and outside them some people find their side effects continue after stopping, or get worse.

Neither the UK nor the US product information says how long that took. So if you read that side effects clear “within two weeks”, that figure is not from the label.

There is a wider gap too. Clinical trials do not routinely include follow-up to check that sexual side effects have gone, as the authors of the 2022 diagnostic criteria note.

What if side effects do not go away?

For some people, sexual side effects last long after the last tablet. This is now written into the official warnings.

US label

Sexual problems that "continued after discontinuation", added in 2011 and 2012

UK leaflet

Persistent erection, sex drive and ejaculation problems after stopping. Frequency unknown

MHRA, 2024

Sexual dysfunction "has persisted even after treatment was stopped"

NHS

Side effects "can sometimes carry on even after you stop"

Researchers call this post-finasteride syndrome, or PFS. One of the 2022 diagnostic criteria is that the problem is still there 3 months or more after stopping. Sexual problems that clear after stopping are not PFS, the criteria add.

Two small studies at George Washington University in the US looked at how long it lasts. Both included only men whose side effects had lasted at least 3 months after stopping.

• A 2011 study of 71 men: their symptoms had lasted 40 months on average, counted from stopping to the interview.
• A 2012 study assessed 54 men a second time, 9 to 16 months later. Persistent sexual side effects were still present in 96% of them.

These numbers describe men who already had lasting symptoms. They cannot tell you how likely this is to happen to you.

How many people get their sexual function fully back has never been properly investigated, the 2022 criteria say. Our patient registry records each person’s symptoms over months and years, which a single side effect report cannot. That is the kind of record this question needs.

Lasting side effects can affect mood as well. In a 2012 study of 61 former users with lasting sexual side effects, 46 had symptoms of depression. That compared with 3 of 29 men with hair loss who had never taken finasteride.

Can side effects start after you stop?

In some cases, according to the 2022 diagnostic criteria. They cover finasteride, some antidepressants and isotretinoin together. They say a lasting sexual problem may only appear once the drug is stopped, or a mild one may get worse. The authors add that data on when symptoms start are limited.

The UK and US product information for finasteride do not describe a withdrawal reaction. Even so, in its 2024 safety update the MHRA asked people reporting side effects to say if a side effect “continued or started after treatment was stopped”.

In patient communities, symptoms that start or get worse suddenly after stopping are often called a “crash”. If that has happened to you, tell your doctor, and include it in any report you make.

Should you taper finasteride or stop all at once?

No study has answered this. We searched the medical literature and found none that compares tapering finasteride with stopping at once. Neither the UK prescribing information nor the US label gives a tapering schedule.

You will find strong opinions online, both ways. Without a study, neither side can show it is right.

Questions to ask your prescriber:

• Could what I am feeling be a side effect of finasteride?
• Does the way I stop matter in my case, and why?
• What changes should I tell you about afterwards?

When should you talk to a doctor?

Whenever sexual side effects bother you, whether you still take finasteride or have stopped. The NHS notes that some men have reported sexual side effects that continued to bother them even after they stopped. It advises talking to your doctor.

Low mood needs attention too. The European Medicines Agency’s 2025 review says finasteride tablets can cause depressed mood, depression or suicidal thoughts. For low mood, the NHS says to call your doctor or 111 now. If you have thoughts of harming yourself, it says to call 999 or go to A&E now.

Take these with you:

• The leaflet or patient card from the pack. Your doctor may not have come across these warnings, and the leaflet lists them.
• Your dose, and roughly when you started and stopped.
• What changed, and when. Say whether it started or continued after stopping.
• Any change in mood, even if it seems unrelated.

Our guide on how to approach your doctor about PFS has more on that conversation.

You can also report it yourself. A Yellow Card report tells the UK regulator about one reaction. The registry adds what happens after that, over time, which is the part research is missing.

Alex’s story

Alex, a pharmacy student, describes the sexual, physical and neurological side effects that continued after he stopped finasteride. The interview is 39 minutes long, from the Moral Medicine channel.

What we cannot tell you

We are a patient charity, not clinicians. We cannot tell you whether to stop finasteride, keep taking it or taper it.

We cannot give you your chance of lasting side effects either. The UK product information says the frequency of reactions reported after approval cannot be determined. The 2022 criteria say the incidence of PFS is unknown.

And if your symptoms have lasted, we cannot promise they will clear. We cannot tell you they are permanent, either.

If you are struggling with your mental health, the Samaritans are on 116 123 in the UK, free, at any hour. In the US, call or text 988.