Flibanserin is licensed for one specific diagnosis, and the label is unusually strict about what that is. It treats acquired, generalised hypoactive sexual desire disorder (HSDD) in women under 65, characterised by low sexual desire causing marked distress or interpersonal difficulty, and only where the low desire is not due to a co-existing medical or psychiatric condition, or problems within the relationship.

Those exclusions are the article. Most low desire has a cause, and where a cause exists this is not the treatment for it. The label is also explicit that it is not indicated to enhance sexual performance and is not indicated in men.

There is a boxed warning, and it is about alcohol.

Key takeaways

  • It treats one narrow diagnosis, acquired generalised HSDD, not low desire in general.
  • “Acquired” means it developed, in someone who previously had normal desire. “Generalised” means it is not confined to a particular partner or situation.
  • The label excludes other causes. If low desire is due to another medical or psychiatric condition, or to relationship problems, this is not the treatment.
  • Boxed warning: alcohol. Taking it and alcohol close together increases the risk of severe hypotension and syncope, meaning dangerously low blood pressure and fainting.
  • Wait at least two hours after one or two standard drinks before taking it at bedtime, and skip the dose after three or more.
  • Contraindicated with moderate or strong CYP3A4 inhibitors, a common group of medicines.
  • Contraindicated in liver impairment.
  • Not for women 65 or over, not for children, not for men.

What is HSDD, and is that what I have?

Low sexual desire that causes marked distress, that developed rather than always being present, and that is not explained by something else.

The three qualifying words in the label do a great deal of work:

  • Acquired. The desire was there before and has gone. Someone who has always had low desire is a different situation.
  • Generalised. It applies broadly, not only with one partner, in one setting, or at one time.
  • Causing marked distress or interpersonal difficulty. Low desire that does not trouble you is not a disorder.

Then the exclusions. The label states the diagnosis applies where the low desire is not due to a co-existing medical or psychiatric condition, problems within the relationship, or other identified causes.

That means the diagnosis is largely made by exclusion, and the exclusions are common. Which is exactly why this needs assessing rather than self-diagnosing.

What actually causes low desire?

Usually something, and often something treatable.

Before a diagnosis of HSDD is reasonable, the things that commonly explain low desire have to be considered:

  • Menopause and perimenopause, where falling hormones affect desire directly and indirectly through sleep, mood and vaginal discomfort. Covered in menopause and HRT.
  • Thyroid disease, which causes fatigue and low mood and is diagnosed by blood test. Covered in thyroid problems.
  • Depression and anxiety, both of which reduce desire.
  • Medicines, notably antidepressants, which commonly affect desire and where a change may resolve it. Covered in antidepressants.
  • Pain or discomfort during sex, which is a physical problem being expressed as an apparent desire problem.
  • Exhaustion, chronic illness, and the ordinary weight of life.
  • Relationship factors, which the label names explicitly as an exclusion.

The NHS makes a related point about low libido around the menopause: it has many possible causes including relationship difficulties, how you feel about yourself, and physical discomfort. Treating it as purely chemical misses most of that.

None of this is a way of saying low desire is not real or does not deserve attention. It is a way of saying that the useful first step is finding out why, because most of those causes have their own treatment and several are more effective than treating desire directly.

What does the boxed warning say?

That alcohol taken close in time to flibanserin increases the risk of severe hypotension and syncope.

The label’s boxed warning is headed hypotension and syncope in certain settings, and it has three limbs.

Alcohol. Using flibanserin and alcohol together close in time increases the risk of severe low blood pressure and fainting. The label’s counselling instruction is specific: wait at least two hours after one or two standard alcoholic drinks before taking it at bedtime, or skip that night’s dose if three or more standard drinks have been consumed.

CYP3A4 inhibitors. Taking it with moderate or strong CYP3A4 inhibitors raises flibanserin levels and can cause severe hypotension and syncope, so their use is contraindicated in patients taking it. That group includes some antifungals, some antibiotics and some other common medicines, which is why the full medicine list matters rather than just the obvious ones.

Liver impairment. Use in patients with hepatic impairment raises flibanserin levels and can cause severe hypotension and syncope, so it is contraindicated in hepatic impairment.

Syncope means fainting, and fainting from low blood pressure carries the injury risk of any sudden collapse. This is not a theoretical interaction to note and move past.

How is it taken, and who is it not for?

At bedtime, daily, and not by several groups the label names.

It is taken at bedtime rather than before sex, which surprises people who expect it to work like a PDE-5 inhibitor for men. It is not an on-demand medicine, and it is not an equivalent of anything used for erectile dysfunction.

The label’s limitations of use are explicit:

  • Not indicated to enhance sexual performance.
  • Not indicated in men.
  • Not indicated for use in paediatric patients.
  • Not indicated for the treatment of HSDD in geriatric patients, and the indication itself specifies women less than 65 years of age.

If you have been offered it outside those boundaries, that is worth questioning.

What are the alternatives?

Treating the cause, and in some cases hormonal approaches.

Where a cause is identified, treating it is the more effective route: hormone treatment where menopause is the driver, thyroid treatment where that is the cause, changing an antidepressant where the medicine is responsible, or treating pain where sex is uncomfortable.

Testosterone is used for low libido in some women. The NHS notes that testosterone gel or cream can help improve low sex drive for some, and that it may be available on prescription from a menopause specialist. That is a specialist decision.

Psychological and relationship approaches are effective and are not a lesser option. Where the label itself excludes relationship problems from the diagnosis, it is implicitly pointing at where the answer lies in those cases.

Do and don’t

Do:

  • Get the cause assessed before treating desire directly.
  • Ask about thyroid, menopause, mood and current medicines.
  • Tell the prescriber every medicine you take, because of the CYP3A4 contraindication.
  • Follow the alcohol timing rule precisely if you are taking flibanserin.
  • Take it at bedtime, as directed.

Don’t:

  • Don’t drink and take it close together.
  • Don’t take it with a moderate or strong CYP3A4 inhibitor.
  • Don’t take it if you have liver impairment.
  • Don’t expect it to work like an on-demand medicine.
  • Don’t assume low desire is a disorder if it does not distress you.

Frequently asked questions

Is this the female equivalent of a PDE-5 inhibitor? No, and the comparison misleads. PDE-5 inhibitors act on blood flow and are taken before sex; flibanserin acts on the central nervous system and is taken nightly. The label also states it is not indicated to enhance sexual performance.

Can I have any alcohol at all? The label does not ban alcohol outright; it sets timing rules. Wait at least two hours after one or two standard drinks before the bedtime dose, and skip the dose entirely after three or more. Given the risk is severe hypotension and fainting, this is a rule to follow exactly rather than approximately.

What if I am over 65? It is not indicated for HSDD in geriatric patients, and the licensed indication specifies women under 65. Low desire after 65 is still worth assessing, but this is not the medicine for it.

Where to go next

The women’s health and hormone therapy categories list what is stocked here. If menopause is a possible factor, menopause and HRT covers the symptoms and treatment, and thyroid problems covers a cause that is easily missed.

MedicForce option: our listings show active ingredient and strength, which is what a prescriber will use when discussing options.

Label statements quoted above, including the indication, the limitations of use and the boxed warning, are from the approved product information for Addyi (flibanserin).