An HS flare-up is a period when hidradenitis suppurativa (HS) becomes actively inflamed, producing painful lumps, abscesses, or draining sores in areas where skin rubs together. These flares follow a relapsing pattern: they erupt, partially or fully resolve, then return weeks or months later. Over time, repeated flares can create tunnels under the skin and permanent scarring.
What Happens Inside Your Skin During a Flare
HS starts with blockages in hair follicles. When a follicle becomes plugged, it eventually ruptures beneath the skin’s surface, spilling its contents into surrounding tissue. Your immune system responds aggressively, flooding the area with inflammatory signals. The key drivers are specific immune pathways involving proteins that amplify inflammation and recruit more immune cells to the site. This creates a self-reinforcing cycle: inflammation damages tissue, which triggers more inflammation.
That cycle is why HS flares tend to worsen with each recurrence. The repeated immune assault gradually destroys normal tissue architecture and can form sinus tracts, which are tunnel-like channels connecting separate lesions beneath the skin. These tracts make future flares more likely in the same area because they provide ready-made pathways for inflammation to spread.
What a Flare Looks and Feels Like
Many people notice early warning signs before a visible flare appears. A localized burning, tingling, or deep itch in a familiar spot often signals that a new lesion is forming. Within a day or two, a firm, painful lump develops under the skin.
From there, a flare typically progresses through a recognizable sequence:
- Nodules: Deep, pea-sized to marble-sized lumps that are tender to the touch and may feel warm.
- Abscesses: The nodule fills with fluid and becomes more painful, sometimes swelling to the size of a golf ball. The pressure can make sitting, walking, or raising your arms extremely uncomfortable depending on the location.
- Drainage: The abscess eventually opens and releases fluid that may be blood-tinged or pus-like, often with a noticeable odor. Pus is common in HS and does not automatically mean the area is infected.
- Blackheads: Clusters of double-barreled blackheads (two connected openings) can appear alongside or between flares, particularly in areas with dense hair follicles.
The most common locations are the armpits, groin, inner thighs, buttocks, and under the breasts. These areas experience the most friction and moisture, both of which worsen the condition. After a flare resolves, the skin may heal with ropelike scars or pitted areas that become permanent landmarks of prior episodes.
How Long Flares Last
Individual flares vary widely. A mild nodule may resolve in a week or two, while a deep abscess can persist for several weeks before draining and slowly healing. HS follows a cycle of flaring, going quiet for a period, then returning. In women, flares often intensify just before a menstrual period and ease afterward, pointing to hormonal influence on the disease.
Early in the disease, quiet periods between flares may last months. As HS progresses, the gap between flares tends to shrink. Eventually, some people reach a point where flares overlap or never fully resolve, leaving continuously active disease. This progression is not inevitable, but it underscores why early, consistent management matters.
Common Triggers
HS flares are not entirely random. Several factors can push the disease from a quiet phase into an active one. Smoking tobacco is one of the strongest modifiable risk factors, as it promotes the type of inflammation that drives HS. Mechanical friction from tight clothing, skin-on-skin rubbing, or shaving irritates follicles and can initiate a flare in a vulnerable area.
Hormonal shifts play a significant role, which is why flares often track with menstrual cycles. Stress, heat, and excessive sweating also appear as common triggers. Some people identify specific dietary factors that worsen their flares, though the link between diet and HS varies from person to person. Tracking your flares alongside potential triggers in a journal can help you identify your personal pattern over time.
Stages of Severity
Doctors classify HS severity using the Hurley staging system, which is helpful for understanding where your disease falls on the spectrum:
- Stage I: Isolated abscesses without sinus tracts or scarring. Flares appear in one or a few spots and resolve without connecting to each other.
- Stage II: Recurrent abscesses in multiple areas with some sinus tract formation and scarring. Lesions may start connecting beneath the skin.
- Stage III: Widespread involvement with extensive sinus tracts and scarring across an entire region. Flares are nearly continuous.
Most people with HS remain at Stage I or II, but progression can happen when the disease goes untreated for years. Knowing your stage helps you and your dermatologist choose the right level of treatment.
Pus vs. Infection: Knowing the Difference
One of the most confusing aspects of HS flares is that draining pus-like fluid is a normal part of the disease. It does not necessarily signal a bacterial infection. Secondary infections can happen, but they layer additional symptoms on top of a typical flare. Signs that suggest infection rather than a standard flare include spreading redness beyond the immediate lesion, a sudden spike in pain out of proportion to the size of the lump, fever, and red streaking on the skin radiating outward from the sore. These warrant prompt medical attention.
Managing Pain During a Flare
Flare pain ranges from a dull ache to sharp, throbbing pressure that interferes with basic movement. For mild to moderate flares, over-the-counter pain relievers like ibuprofen or acetaminophen can take the edge off. Ibuprofen has the added benefit of reducing some inflammation. Topical numbing products containing lidocaine, applied directly to the skin over a painful nodule, provide temporary targeted relief.
Warm compresses are one of the most effective home remedies. Applying a clean, warm cloth to the area for 10 to 15 minutes several times a day can ease pain and encourage a lesion to drain on its own. Loose-fitting clothing reduces friction and pressure on active flares. Keeping the skin cool and dry between compresses also helps prevent irritation from escalating.
For flares that don’t respond to these measures, prescription options exist. Topical or oral antibiotics can reduce the bacterial load that fuels inflammation. Hormonal medications, including certain birth control pills, address the hormonal component of flare cycles. For moderate-to-severe HS, biologic medications that block specific inflammatory proteins are available; one such treatment is the only FDA-approved medication specifically for HS. In cases where pain becomes chronic and difficult to control, a dermatologist may refer you to a pain specialist.
Caring for Draining Lesions
When a flare opens and drains, proper wound care prevents secondary infection and protects the skin from further damage. Use a gentle antiseptic wash, such as one containing chlorhexidine or benzoyl peroxide, starting once a week and increasing to daily if your skin tolerates it. Pat the area dry rather than rubbing.
Avoid using washcloths, loofahs, or any textured material on affected areas, as these irritate already-damaged skin. Never squeeze, pop, or manually drain a lesion. This forces material deeper into surrounding tissue and can worsen the flare or trigger new ones nearby. Avoid shaving or using hair-removal creams on active areas. Cover draining sores with a clean, non-stick dressing and change it when it becomes saturated. Keeping the wound clean and protected gives the skin the best chance to heal with minimal additional scarring.
Emotional Impact of Flares
The physical symptoms of HS are only part of the picture. The location of lesions in intimate areas, combined with drainage and odor, creates a level of embarrassment that can reshape someone’s daily life. Many people with HS avoid social situations, physical intimacy, or activities like swimming during flares. Anxiety about when the next flare will strike and depression from chronic pain and self-consciousness are common. These emotional effects are a recognized part of the disease, not a personal failing, and addressing them with a mental health professional can be just as important as treating the skin itself.