Qbrexza Side Effects: What to Expect and When to Call Your Doctor

Qbrexza (glycopyrronium cloth, 2.4%) is a topical anticholinergic medication that works by blocking the nerve signals that activate your sweat glands. It's FDA-approved for primary axillary hyperhidrosis (excessive underarm sweating) and can be highly effective — but like all anticholinergic drugs, it comes with a distinct set of side effects that patients should understand before starting treatment.

This guide covers every documented side effect of Qbrexza, from the common and manageable to the rare but serious. Knowing what to expect — and when to stop using the medication and contact your healthcare provider — is key to using Qbrexza safely.

Why Does Qbrexza Cause These Side Effects?

Qbrexza's active ingredient, glycopyrronium, works by competitively blocking acetylcholine receptors on sweat glands. Acetylcholine is a neurotransmitter that the body uses to activate many functions — not just sweating. Although Qbrexza is applied topically and a relatively small amount is absorbed into the bloodstream, some systemic absorption does occur, which is why anticholinergic side effects can appear in other parts of the body.

The side effects described below were observed in Phase 3 clinical trials (ATMOS-1 and ATMOS-2) involving 459 subjects treated with Qbrexza once daily, as well as from post-marketing surveillance.

Common Side Effects (Reported in ≥2% of Clinical Trial Subjects)

These are the most frequently reported side effects of Qbrexza. They are typically mild to moderate and may lessen over time or with adjusted application technique:

• Dry mouth — the most commonly reported side effect; can range from mild dryness to severe inability to produce saliva. Increasing water intake and staying hydrated can help. Some patients find that spacing doses (e.g., every other day) reduces severity.
• Pupil dilation (mydriasis) — occurs primarily from accidental eye contact with the cloth or with hands that haven't been washed after application. Wash hands immediately with soap and water after applying and discarding the cloth.
• Sore throat — mild pharyngeal dryness or irritation reported in some patients.
• Local skin reactions — redness, burning, stinging, or itching at the application site (underarm area). Some patients find this manageable; others, who were previously on Drysol, note that Qbrexza is generally less irritating.
• Headache — reported in some patients, usually mild.
• Urinary problems/hesitancy — difficulty initiating urination, a common anticholinergic effect. See the serious side effects section below for urinary retention, which requires immediate attention.
• Blurred vision — can occur due to accidental eye exposure or anticholinergic effects. Do not drive if blurred vision occurs; see the serious side effects section below.
• Nasal, throat, eye, and skin dryness — generalized dryness from anticholinergic effects.
• Constipation — slowed gut motility, another common anticholinergic effect. Staying well hydrated and maintaining adequate dietary fiber can help.

Serious Side Effects: Stop Using Qbrexza and Call Your Doctor Immediately

The following are less common but serious side effects that require you to stop using Qbrexza and contact your healthcare provider right away:

• Urinary retention: Inability to empty your bladder completely, distended (full) bladder, or severe difficulty urinating. This is especially dangerous in men with prostate enlargement or bladder-neck obstruction. Stop Qbrexza immediately and seek medical attention.
• Heat illness (hyperpyrexia/heat stroke): Because Qbrexza reduces sweating, your body may have difficulty regulating temperature in hot environments. Watch for lack of sweating across your whole body in hot weather. Stop using Qbrexza and avoid hot conditions if this occurs. Get immediate help if you develop fever, confusion, rapid heart rate, or other heat stroke symptoms.
• Blurred vision (persistent or driving-related): If blurred vision occurs, stop Qbrexza and do not drive, operate machinery, or perform hazardous work until your vision clears. Contact your provider.
• Severe allergic reactions: Rare but possible. Get immediate emergency help if you develop hives, difficulty breathing, or swelling of the face, lips, tongue, or throat.

Tips for Managing Qbrexza Side Effects

• Always wash your hands immediately after applying and discarding the cloth — this is the most important step to prevent accidental eye exposure and pupil dilation.
• Stay well hydrated to manage dry mouth and constipation.
• Avoid hot environments and watch for signs of reduced sweating across your body, especially in summer.
• Some patients reduce frequency from daily to every other day if side effects are too disruptive, while maintaining good sweat control. Ask your prescriber if this is appropriate for you.
• Discard used cloths safely in household trash out of reach of children — accidental exposure can cause pupil dilation and blurred vision in anyone who touches the used cloth.

Contraindications: Who Should Not Use Qbrexza?

Do not use Qbrexza if you have any of the following conditions, as the anticholinergic effects could make them significantly worse:

• Glaucoma
• Paralytic ileus or severe bowel obstruction
• Severe ulcerative colitis or toxic megacolon
• Myasthenia gravis
• Sjogren's syndrome
• Unstable cardiovascular status in acute hemorrhage

Also read our guide on Qbrexza drug interactions to understand which medications should not be used alongside Qbrexza. And if you're struggling to fill your prescription, medfinder can help locate pharmacies near you that have it in stock.