When someone with Alzheimer’s disease is taking anti-amyloid monoclonal antibodies—medications like lecanemab or donanemab designed to slow cognitive decline—healthcare providers monitor for a specific complication called ARIA, or Amyloid-Related Imaging Abnormalities. ARIA appears on brain MRI scans and comes in two forms: ARIA-E, which is brain swelling (edema), and ARIA-H, which is microhemorrhages—tiny bleeds in brain tissue. These imaging changes can happen without symptoms, but when they do cause symptoms, some of those symptoms demand an immediate call to the medical team, not a scheduled appointment.
The urgency depends on what’s happening. A mild headache might warrant a phone call during business hours; sudden confusion, severe headache with vision changes, or signs of stroke require emergency services. Understanding which ARIA symptoms need immediate attention versus which can wait is critical because these medications are increasingly prescribed, and caregivers need to know the difference between manageable side effects and medical emergencies.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Table of Contents
- What Are the Most Dangerous ARIA Symptoms That Demand an Urgent Call?
- Neurological Emergency Symptoms That Require Immediate Medical Evaluation
- Behavioral and Cognitive Changes That Signal Urgent ARIA Complications
- How to Distinguish Between Symptoms That Can Wait and Those That Require Emergency Services
- Medication Interactions and Monitoring That Impact When to Escalate Care
- Communication with the Medical Team When ARIA Symptoms Occur
- Caregiver Preparation and When to Seek Second Opinions
- Frequently Asked Questions
What Are the Most Dangerous ARIA Symptoms That Demand an Urgent Call?
Severe or worsening headache is one of the most common warning signs of aria-E and needs to be reported promptly, especially if it’s different from headaches the person has had before. A headache that wakes someone from sleep, is accompanied by fever, neck stiffness, or confusion, or that doesn’t respond to over-the-counter pain relief should trigger an urgent call—these could indicate increased brain swelling or infection. If the headache is accompanied by vision changes, weakness on one side of the body, slurred speech, or difficulty walking, this could signal a stroke or severe brain swelling and requires emergency services (911 in the US).
Confusion or delirium that develops suddenly or worsens significantly over hours is another red flag. While Alzheimer’s itself causes progressive cognitive decline, a sudden or acute change—someone becoming unable to recognize family members, speaking incoherently, or becoming agitated in ways that are new—suggests ARIA or another acute medical issue. This differs from the gradual decline families see over months; it’s a shift that seems to happen over hours to a day. Seizures, even a first seizure, warrant immediate emergency care, as do signs of stroke like facial drooping, arm weakness, or speech difficulty.
Neurological Emergency Symptoms That Require Immediate Medical Evaluation
Severe dizziness or loss of balance that’s new or dramatically worsened can indicate ARIA-H with bleeding or ARIA-E with swelling affecting balance centers in the brain. If someone suddenly can’t stand without falling, becomes unable to coordinate movements, or experiences vertigo severe enough that they can’t safely move around the house, this requires an urgent call. Compare this to mild dizziness when standing quickly—common in older adults—versus vertigo so severe the person cannot walk straight or falls repeatedly; the latter is what demands immediate attention.
Vision changes also matter, particularly if they’re sudden. Blurred vision, double vision, loss of vision in part of the visual field, or difficulty tracking objects should be reported urgently, especially if they develop over hours rather than days. The limitation here is that visual symptoms can sometimes be attributed to other causes—presbyopia, cataracts, or retinal problems—so caregivers should clarify the timeline. If someone who was seeing fine this morning suddenly can’t read or see the right side of their visual field, that’s urgent; if vision has been slowly declining over weeks, it might be another issue entirely.
Behavioral and Cognitive Changes That Signal Urgent ARIA Complications
Extreme behavioral changes—aggression, extreme agitation, or apathy so severe the person stops eating or responding—can sometimes accompany significant ARIA-E. This is distinct from the behavioral changes that are part of Alzheimer’s disease progression; it’s an acute shift where the person becomes almost unrecognizable in their temperament over a short timeframe. one example would be someone who was previously cooperative and calm becoming violent or completely unresponsive within 24 hours, especially if this coincides with other neurological changes.
Inability to swallow or significant difficulty swallowing can indicate involvement of areas of the brain that control this vital reflex. If someone starts coughing when drinking, seems to be aspirating food or liquid, or complains that swallowing is painful or impossible, this warrants urgent evaluation. Aspiration—when food or liquid enters the airway instead of going down the esophagus—can lead to aspiration pneumonia, a serious infection. Unlike difficulty swallowing that develops gradually over months with Alzheimer’s progression, sudden swallowing problems suggest something acute is happening.
How to Distinguish Between Symptoms That Can Wait and Those That Require Emergency Services
The key difference is timing and severity. If symptoms developed gradually over weeks or months, or if they’re mild and stable, a call to the neurologist’s office during business hours is appropriate. If symptoms developed suddenly over hours, are severe, or suggest stroke or seizure, call 911. For example: a person having one or two episodes of mild confusion over a day might warrant a phone call to the doctor; a person who can no longer speak coherently or recognize family members warrants emergency services.
The tradeoff is that caregivers sometimes hesitate to call for emergencies out of fear of “overreacting” or burdening medical personnel. This hesitation can be dangerous. In the context of someone taking anti-amyloid monoclonal antibodies, any sudden neurological change should be treated seriously until proven otherwise. It’s better to call 911 and have the person checked out than to wait and hope symptoms improve. Emergency departments can perform imaging to determine if ARIA-E or ARIA-H is present and can provide appropriate treatment rapidly.
Medication Interactions and Monitoring That Impact When to Escalate Care
Some individuals taking anti-amyloid monoclonal antibodies are also on blood thinners like warfarin or antiplatelet medications, which increase the risk of microhemorrhages (ARIA-H). If someone on these medications experiences any signs of bleeding—easy bruising, nosebleeds, blood in urine or stool, or bruising that appears without an obvious injury—these should be reported to the medical team, though not necessarily as an emergency unless accompanied by other acute symptoms. The limitation is that minor bruising can be normal in older adults, so caregivers should look for unusual patterns or severity.
Regular MRI monitoring is part of the protocol for people on these medications, and imaging can show ARIA before symptoms develop. Missing these appointments or delaying imaging defeats this safety net. If imaging shows ARIA-E or ARIA-H, the medical team may adjust the medication dose, space out infusions, or pause treatment entirely. Knowing the results of recent imaging helps interpret new symptoms—if imaging from last month showed no ARIA but someone suddenly has a severe headache, the urgency may be different than if imaging already showed significant brain swelling.
Communication with the Medical Team When ARIA Symptoms Occur
When calling the neurologist or pharmacist about potential ARIA symptoms, specificity matters. Rather than saying “They’re confused,” describe what that looks like: “She doesn’t recognize me and is calling out names of people who died 20 years ago, and this started this morning.” Rather than “He has a headache,” note: “He says his head feels like it’s splitting, he’s had it since 4 AM, and it’s not better after acetaminophen or ibuprofen.” Having a list of what to report—when the symptom started, how quickly it worsened, what makes it better or worse, what other symptoms have appeared—helps the medical team triage appropriately. A warning: do not wait for a doctor’s callback if symptoms suggest an emergency.
Call 911 immediately and tell the emergency responders that the person is on an anti-amyloid monoclonal antibody. This information is crucial for the emergency team because it narrows the differential diagnosis and prompts appropriate imaging and treatment. Some emergency departments may not be immediately familiar with ARIA, so mentioning it explicitly can ensure the person receives the right workup.
Caregiver Preparation and When to Seek Second Opinions
Before starting treatment with these medications, caregivers should ask the prescribing neurologist specifically which symptoms warrant urgent calls and which warrant emergency services. Getting this information in writing—a printed or saved list—provides a reference when stress and fear make memory unreliable. Ask whether the person’s specific medical history (prior strokes, existing brain lesions, concurrent blood thinner use) changes the risk profile for ARIA.
Some caregivers have found it valuable to arrange a pre-treatment conversation with the infusion center and the neurology office to ensure all parties understand the monitoring plan. If a person is receiving infusions at a hospital-affiliated center, that facility often has protocols already in place, but confirming this prevents gaps. If symptoms appear and the immediate medical team dismisses them as “just Alzheimer’s,” a second opinion from another neurologist familiar with ARIA can clarify whether imaging or symptom evaluation is needed.
Frequently Asked Questions
What’s the difference between ARIA-E and ARIA-H, and do they have different symptoms?
ARIA-E is brain swelling and often causes headache, confusion, or vision changes. ARIA-H is microhemorrhages and may have fewer obvious symptoms initially but can cause sudden neurological changes. Both can be serious and require medical attention, though the symptoms differ slightly.
My parent is on an anti-amyloid monoclonal antibody but has no MRI evidence of ARIA. Are they safe?
Imaging can show ARIA before symptoms appear, which is why regular monitoring matters. However, not everyone develops ARIA, and the risk depends on genetics, age, and other factors. Continue regular monitoring appointments and watch for new symptoms, but lack of ARIA on imaging is reassuring.
Can ARIA be treated once it develops?
Yes. Treatment usually involves pausing the medication, adjusting the dose, or spacing out infusions longer. In some cases, corticosteroids may be used to reduce brain swelling. The neurologist decides the best approach based on severity and the person’s overall health.
How quickly can ARIA symptoms develop?
ARIA can develop at any point during treatment, though some cases appear shortly after starting or increasing the medication dose. This is why symptom vigilance remains important throughout treatment, not just at the start.
Should caregivers ever hesitate to call 911 for potential ARIA symptoms?
No. If you suspect stroke, severe neurological changes, seizures, or other emergencies, call 911. The emergency team can determine whether ARIA is present through imaging and treatment. Waiting and hoping is not safe.
What should I tell emergency responders when calling?
Tell them the person is on an anti-amyloid monoclonal antibody for Alzheimer’s treatment and describe the symptoms. This helps the emergency team perform the right imaging (usually MRI) and recognize ARIA as a possible cause of acute symptoms.
