For some, HS flares come on suddenly. But others may experience early warning signs — and they don’t always involve the skin.

Hidradenitis suppurativa (HS) is a chronic inflammatory skin condition caused by clogged and ruptured hair follicles. It’s characterized by painful lumps, cysts, abscesses, and sinus tracts (tunnels of infection beneath the skin’s surface).

If you’ve been diagnosed with HS, your symptoms and when they appear can vary. Times where symptoms worsen are known as flares, and they can happen for a variety of reasons, sometimes without clear cause.

Some, but not all, people living with HS develop warning signs a flare is about to happen. These are known as “prodromal symptoms” because they occur during the prodromal (or earliest) phase of HS development.

Here’s what that might look like.

Fatigue is a general sense of exhaustion that goes beyond sleepiness or being tired. In HS, it can appear as anything from general mental and physical fatigue to reduced activity and motivation.

While anyone can experience fatigue, it’s one of the most common full-body warning signs reported in HS, according to findings from a 2017 study.

A 2024 study also found that fatigue was predictive of HS severity. According to this study, the more significant the fatigue, the more likely that the HS symptoms would be severe.

According to a review from 2022, approximately half of people seen in emergency departments with HS report flu-like symptoms before a flare. Fever and chills are among the flu-like symptoms possible in HS. A true fever, indicated by elevated body temperature, can indicate a serious infection is present.

In adults, a true fever occurs when your body temperature rises above 99.1°F (37.3°C). Low-grade fevers fall under 100.4°F (38°C), while high-grade fevers are 102.4°F (39.1°C) or higher.

Fevers are often accompanied by chills as your body reduces blood flow to the skin surface in order to build and conserve heat. This can make you feel colder, despite having an increased body temperature.

It’s also possible to feel like you have a fever without actually having one. For some people, a prodromal fever in HS may actually be part of malaise. Malaise is a general sense of illness that can include fever-like sensations without an actual rise in body temperature.

In the 2017 research, nausea was the least reported warning sign of an HS flare, affecting approximately 2% of people surveyed.

Similar to other flu-like symptoms, nausea shouldn’t be dismissed as “just a warning sign” of HS. Secondary infections are a possible complication of HS. They develop when bacteria present on your skin enter open skin lesions, multiplying in the warm, moist environment.

If you have a severe infection, nausea may crop up. If an infection is present at the same time you experience a flare, nausea could be more than just a prodromal sensation.

The majority of people with prodromal warning signs of HS experience skin changes, particularly:

  • erythema (skin redness)
  • paresthesia (a tingling or prickling sensation)
  • pruritus (skin itching)

These symptoms typically appear within 24 hours before developing a skin lesion and are common because they’re directly related to how HS progresses in your skin.

HS begins when a hair follicle becomes clogged with a protein called keratin. During this time, as the HS nodule is emerging, your skin can naturally display warning signs of an inflammatory process, like itching and redness.

Around 11% of people in the 2017 research reported headaches among their HS warning symptoms.

Sensations can include:

  • dull, aching pain
  • pounding or throbbing pain
  • stabbing, sharp pain
  • uncomfortable pressure

Headaches can also be accompanied by nausea, sensitivity to light, and visual disturbances.

People assigned female at birth may notice HS flares align with the days right before menstruation, known as the premenstrual period. In a 2020 study including 283 participants, 78.9% indicated their HS flared during the week before their period.

If you know the premenstrual time is when you can expect a flare, tracking your menstrual cycle can be useful. Learning to recognize changes in your body that indicate the premenstrual time frame may also help.

The premenstrual period comes at the end of the luteal phase of your cycle when your body begins to prepare the uterine lining to receive a fertilized egg.

During the luteal phase, you may notice:

  • breast tenderness
  • cramping
  • bloating
  • headaches
  • fatigue
  • food cravings
  • mood changes

While these symptoms don’t indicate the start of an HS flare, they can be warning signs that you’re entering the part of your menstrual cycle where a flare is most likely to occur.

For most people, living with HS means coping with symptom flares. Even with treatment, there can be times when lumps, cysts, and abscesses become worse than usual.

For many people, HS flares come with prodromal warning symptoms, or signs that occur before the flare develops in full force. While skin-related symptoms are common, full-body symptoms like fatigue, malaise, and headaches are also possible.