C fibres and burning pain in vulvodynia

Author: Jessica Lloyd
Senior Vulvovaginal Specialist Naturopath | BHSc(N) | ISSVD, ISSWSH, BSSM, ATMS

Last reviewed: July 30, 2026

There is a special type of pain nerve fibre found around the human body, with the vestibule in the vulva containing many – the C fibre. These fibres may be linked with the specific type of pain associated with vulvodynia, particularly neuroproliferative vulvodynia.

Vulvodynia, chronic vulvar or vestibular pain, may be caused due to an overactivity, oversensitivity, or proliferation of C fibre nerves.¹

C fibres, which are unmyelinated (uncoated, like a bare wire) conduct energy from between 0.5 and 2.0 metres per second. This is in contrast to myelinated (coated, like a power lead that has a rubber or plastic coating) A-delta pain fibres, which conduct between 5 to 30 metres per second.

To put this into context, our very sensitive touch nerves conduct between 35 and 120 metres per second. The faster it can conduct per second, the faster a nerve fibre is.

C fibres respond to broad pain stimulus, like heat or cold (thermal), getting knocked or pinched (mechanical), or metabolic. C fibres cause a slow, long-lasting, burning type of pain, which is precisely the type of pain felt in vulvodynia.

The way these nerves work is that they take a while to build up their pain release, with the excitation building with prolonged stimulus. The A-delta fibre, by comparison, responds to stimuli quickly – sharp, bright pain. These nerve fibres are respectively slow and fast to respond to what is happening, for very good reasons.

This is why we have different types of nerve fibres in different places – where we need to feel a burn quickly, our A-deltas act, and where we just need to back off what we’re doing, the C fibres kick into gear.

C fibres and inflammation

When a C fibre produces pain, it also causes the production of substance P in local tissues. This dilates blood vessels and releases histamine, fulfilling the process of inflammation with more pain and swelling, with the local reaction to deal with whatever is happening.

Why capsaicin may be suggested for vulvodynia symptoms

We have receptors for capsaicin, the compound found in hot peppers, on C fibres, which is why capsaicin cream has been trialled for vulvodynia. Older studies were small and mixed,² but more recent work from a specialist vulvovaginal group is encouraging. In a 2024 survey of patients with neuroproliferative vestibulodynia using a low-dose (0.025%) capsaicin cream — applied after a numbing lidocaine ointment to make it tolerable — 80% managed the full daily application within a week or two, around 64% had less pain, and sexual-distress scores improved significantly. Most avoided surgery.³ It is not for everyone and needs careful patient selection and counselling, but for people who want to avoid a vestibulectomy it is emerging as a promising option.

Frequently asked questions

Why does vulvodynia feel like burning?

The vulval vestibule is rich in C-fibre pain nerves, which produce a slow, long-lasting, burning kind of pain. In vulvodynia these fibres can become overactive, oversensitive, or increased in number.¹

Does capsaicin cream help vulvodynia?

Older studies were small and mixed, but newer research is more promising. In a 2024 study of neuroproliferative vestibulodynia, a low-dose capsaicin cream used with a numbing lidocaine ointment beforehand was tolerated by 80% of patients, reduced pain for around 64%, and helped most avoid surgery. It needs careful selection and counselling, but it is emerging as a real alternative to a vestibulectomy.³

This article is general information and not a substitute for personalised medical advice. If you have ongoing vulval pain, please see an experienced practitioner.