Hidradenitis suppurativa (HS) is a chronic skin condition that affects the sweat glands and hair follicles. Stage 1 is the mildest form of the condition.

HS, or acne inversa, commonly appears where skin touches skin or where there is thick, coarse hair. This can include armpits, under the breasts, or groin.

Doctors use a staging system called the Hurley Staging System to classify HS. There are three stages in total. Early diagnosis and treatment can prevent the condition from progressing to the later stages.

This article provides an in-depth look at stage 1 HS, its causes, symptoms, and treatment.

In the Hurley Staging System, stage 1 refers to the earliest, mildest form of HS.

The first signs of stage 1 HS are usually boil-like lesions or abscesses. A person may have a single, painful lump, or there may be multiple lesions. The lesions can appear anywhere on the body but typically affect the:

  • armpit
  • groin
  • thighs
  • buttocks
  • under the breasts
  • near the genitals
  • around the anus

A person may notice small, firm lumps of bumps in the skin, which can become swollen and inflamed. They may think that the lesion is a deep pimple or acne. These bumps may leak an odorous, yellowish-white fluid filled with bacteria and dead skin cells. Sometimes the lesions resolve, only to recur in the same location.

The Hurley Staging System has three stages:

  • Hurley Stage 1: This is the mildest stage and includes single or multiple boils, abscesses, or nodules. There is no scarring, and tracts between the lesions have not formed.
  • Hurley Stage 2: At this stage, a person has recurrent abscesses. The repetitive healing and reopening of the lesions eventually cause tunnels to form beneath the skin, known as sinus tracts. There is also permanent scarring.
  • Hurley Stage 3: The most severe stage of HS. Multiple, interconnected sinus tracts form beneath the skin, and the person has deep scarring. There is little to no unaffected skin.

A combination of genetic, environmental, and behavioral factors causes HS. Around 33–40% of people with HS have a close relative with the condition, suggesting a genetic component.

Environmental and behavioral factors also contribute. For example, HS is more common in people with overweight or obesity.

Excess weight increases the skin surface area and friction, increases sweat production, and causes hormone changes that experts associate with HS. Metabolic syndrome is more common in people with obesity and is, therefore, more common in HS.

HS is more common in females than males, which may suggest a hormonal influence. Females with HS may notice a fluctuation of symptoms that align with menstrual cycles.

HS is unlikely to go away on its own. The condition is chronic and typically causes recurrent flare-ups. Without treatment, HS will continue to heal and then reappear, sometimes worse than before. Eventually, the symptoms may become more permanent and cause scarring.

However, with the right treatment and lifestyle changes, it is possible to significantly reduce symptoms and improve quality of life.

There is no specific test for HS. Therefore, doctors base a diagnosis on a person’s symptoms, a physical examination, and family history. They may also take swabs from the affected skin to test for bacteria or fungus, which may rule out infections.

Diagnosing HS can be difficult. The early signs can look similar to other conditions, which can result in misdiagnosis. The average delay for a correct HS diagnosis is 7 years.

Doctors may mistake HS for:

Treatment for early HS may involve:

  • Topical antibiotics: These medications can reduce inflammation and promote the healing of lesions. Clindamycin is one of the most effective.
  • Corticosteroid injections: If topical antibiotics are not sufficient or a particular lesion is not healing, a doctor may inject a corticosteroid to reduce inflammation.
  • Punch debridement: This involves minor surgery to physically remove the “roof” of individual abscesses or cysts.

Doctors may also recommend resorcinol, which is a skin peel that helps open up clogged hair follicles and ease inflammation.

Some nonmedical treatments may also help ease symptoms. For example, laser hair removal reduces the number of hair follicles a person has and, therefore, the number of HS lumps that can develop. Botulinum toxin, or Botox, can help treat excessive sweating, which may reduce symptoms.

HS can be distressing, but early diagnosis and treatment can make a difference. A person should not hesitate to consult a doctor if they develop:

  • persistent or recurring lumps
  • tender, inflamed areas
  • pus or fluid drainage
  • itchiness

Medical treatment reduces the risk of complications and permanent scarring.

HS can also affect a person’s mental health and self-esteem. If someone feels persistently down or anxious, they can consider speaking with a doctor or mental health professional.

Support groups or therapists with experience helping those with chronic conditions can provide both practical and emotional support for living with HS.

HS is a chronic skin condition that causes lumps and abscesses in areas such as the armpits, groin, and buttocks.

Doctors classify HS into three stages, with stage 1 being the mildest. At this stage, there is no scarring, and tracts or tunnels have not formed under the skin.

Stage 1 HS treatment typically involves topical antibiotics, corticosteroid injections, or skin peels to reduce inflammation and infection. Nonmedical treatments such as laser hair removal and Botox may also help ease symptoms.