What Is Hard Flaccid Syndrome?

For many people, sexual health is essential to leading a healthy life. It can affect your physical health and your emotional, mental, and social well-being.

Premature ejaculation and erectile dysfunction are among the more common forms of sexual dysfunction. However, there has been increased interest in a new condition: Hard flaccid syndrome (HFS).

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What is hard flaccid syndrome?

HFS is a chronic and painful condition that occurs when your penis is semi-hard when soft (flaccid) and limp when stimulated. Studies report that HFS most commonly affects people in their 20–30s. 

While various webpages and online forums have described the condition, sexual medicine experts don't officially recognize it yet. As a result, the issue remains poorly understood, and it is unknown how many people are affected by HFS.

Subtypes of HFS

HFS can present as two subtypes: 


HFS may occur due to traumatic events¹ to the base of the penis or pelvic floor muscles. A severe injury may have damaged vital nerves and arteries. This significantly affects your pelvic floor muscles and erectile function. 

This can affect blood flow to the penis and may lead to symptoms such as pelvic muscle spasms, semi-rigidity during sex, or numbness when touched.


Similar to other sexual dysfunction, emotional distress and mental health conditions can increase the risk of HFS. Depression and anxiety are common causes. Stress prompts the “fight or flight”² response, releasing stress hormones.

Cortisol, epinephrine, and norepinephrine increase your heart rate and narrow your blood vessels. When the stress becomes chronic (repeated), the constant narrowing of blood vessels can reduce blood flow to the penis and worsen your symptoms. 

Symptoms of hard flaccid syndrome

Symptoms can vary from person to person. However, common complaints include: 

  • Sensory changes: Numbness, coldness, or reduced sensitivity to touch

  • Slight ache or pain at the base of the penis when stimulated

  • Painful ejaculation or urination, especially when standing

  • No morning erections

  • Needing excessive visual stimulation or thoughts to feel sexually stimulated

  • Difficulty getting and keeping erections (erectile dysfunction) 

Causes of hard flaccid syndrome

It is unknown what causes HFS. Scientists believe it may be multifactorial, so it could be a combination of many factors. These may be biological, psychological, lifestyle, or environmental factors. 

Common causes include: 

  • Traumatic events to the penis (e.g., rough sex or masturbation, penis stretching exercises)

  • Injury to the pelvis/pelvic floor muscles

  • Injury to the tailbone

  • Hormonal imbalance in the penile nervous system (facilitates “fight-or-flight” response)

  • Chronic stress, anxiety, or hyperfixation on sexual dysfunction 

  • Chronic pelvic pain syndrome

Who is likely to be affected by HFS?

One study³ aimed to understand HFS by examining 152 threads from 12 online forums. 

Based on their observations, HFS is likely to affect men aged 20—30 who have experienced a traumatic event and are now experiencing the symptoms of HFS. 

HFS causes may also increase your chances of developing HFS, particularly if you don’t seek treatment promptly. 


Because of the limited scientific research related to HFS, treatment options are unclear. Experts believe a multimodal approach⁴ is the most efficient treatment, combining medication and several therapies.



Severe depression and anxiety can worsen the development and symptoms associated with HFS. Therefore, your doctor may suggest antidepressants to treat your psychological symptoms.

Antidepressants improve psychological symptoms by increasing levels of certain hormones in your body. Several types of antidepressants are available, including:

  • Selective serotonin reuptake inhibitors (SSRIs)

  • Serotonin/norepinephrine reuptake inhibitors (SNRIs)

  • Tricyclic antidepressants (TCAs)

  • Monoamine oxidase inhibitors (MAOIs)

  • Atypical antidepressants

Your doctor may prescribe an antidepressant as a single treatment or with other therapies. 

While antidepressants can significantly improve psychological symptoms, sometimes they can cause bothersome side effects. These include a reduced sexual drive or erectile dysfunction. It is important to discuss with your doctor the right treatment for you. 

Phosphodiesterase 5 (PDE5) inhibitors 

PDE5 inhibitors⁵ are a medication for treating erectile dysfunction (ED), which occurs when you cannot get or keep an erection. This drug helps you get an erection by relaxing the penile muscles, allowing blood flow to the penis. 

Currently, there are four FDA-approved PDE5 inhibitors available for treatment: 

  • Sildenafil (Viagra)

  • Tadalafil (Cialis)

  • Vardenafil (Levitra or Staxyn)

  • Avanafil (Stendra) 

You should take PDE5 inhibitors one hour before sexual intercourse for peak effectiveness. You should only take them as recommended by your doctor. 

Some clinicians may suggest taking a low dose of PDE5 inhibitor daily to improve penile blood flow and smooth muscle function. Daily use of PDE5 inhibitors in low doses may be suitable if you don’t respond to treatment at first. 

PDE5 inhibitors may increase blood flow if you have HFS. If you are considering PDE5 inhibitors, speak to your doctor to ensure they're right for you. 

This is particularly important if you take other medications such as nitroglycerin, nitrate drugs, or alpha-blockers.



Seeing a physiotherapist is a highly recommended HFS treatment. Rather than just strengthening the pelvic floor muscles, a physiotherapist may provide exercises to relax pelvic floor muscles. 

Your physiotherapist will base your treatment on your needs. Therapy may include Kegel exercises, pelvic yoga, or strengthening of muscles to ease tension from the pelvic floor. 

Your physiotherapist will be able to advise you on how often you should be doing these exercises. 

Physiotherapy and rehab strategies effectively treat HFS-related symptoms such as erectile and ejaculatory dysfunction. 

A case series⁶ found two men could resume pain-free activity and regular sexual intercourse with no pain upon ejaculation. 


Chronic stress, anxiety, and depression can worsen HFS symptoms. Treating them with behavioral therapy may ease HFS. 

Cognitive-behavioral therapy⁷ (CBT) is a psychological treatment that aims to change how you think and behave. If you have psychological HFS, your CBT treatment can be combined with antidepressant medications if necessary.

CBT helps you identify negative thoughts and behaviors before using various problem-solving strategies to change your thought patterns. 

Strategies may include: 

  • Role-playing to prepare for potentially triggering interactions

  • Identifying negative thoughts and replacing them

  • Breaking down problems to target specific things that make you feel anxious or upset

  • Grounding exercises: Deep breathing can bring you back to your surroundings, among many other exercises

There is limited research exploring the relationship between CBT and HFS. However, a review⁸ of CBT on psychological-induced erectile dysfunction found that psychological therapies reduced anxiety and improved erectile function. 

This was more effective when combined with PDE5 medication.  


Low-intensity extracorporeal shockwave therapy is a non-invasive treatment that uses shock waves to treat injured muscle tissue. It is considered a gold-standard treatment for male sexual dysfunction. It's ideal for people who did not respond to previous therapies. 

Shockwave therapy uses a probe or wand to give pulsating shock waves to penile tissue for 15 minutes. Experts suggest it may improve penile blood flow and tissue remodeling, improving erectile function. 

Research⁹ found that men who had shockwave therapy experienced several improvements, including improved penile blood flow and erection duration. Some reported restored penile function for sexual intercourse. 

Given the close association between erectile dysfunction and HFS, shockwave therapy may be a promising treatment for men with HFS. 

Complications associated with HFS

Complications arising from HFS may include: 

  • Erectile dysfunction

  • Embarrassment or low self-esteem

  • Depression or anxiety

  • Unsatisfactory sex life

  • Perineal pain (pain between the genitals and anus)

  • Problems with urination 

How can you prevent HFS?

Physical and psychological elements can cause HFS. That’s why experts recommend a combination of physical and psychological lifestyle modifications to reduce the risk of HFS. These include: 

  • Regular exercise

  • Eating a healthy, nutritious diet

  • Reducing or avoiding smoking

  • Reducing alcohol intake

  • Reducing stress load

  • Practicing meditation or deep breathing

When to see a doctor

If you are experiencing reduced erectile function, pain when ejaculating or masturbating, or a semi-erection when soft, it may be time to see your doctor. They may conduct an assessment to understand your condition and treat any underlying conditions.

Depending on the outcome, they may prescribe medication or refer you to a urologist, psychiatrist, or physiotherapist for further assessment and treatment.

The lowdown

HFS is a condition that refers to a group of symptoms that can significantly affect your physical and emotional well-being. Although sexual medicine is yet to recognize HFS, this doesn’t mean you are out of luck. 

Your doctor can treat any underlying conditions of HFS. If you are experiencing symptoms, speak to your doctor. They will recommend the right treatment option for you.

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