Standing up should be unremarkable. For people on certain antipsychotics, it can mean dizziness, vision blurring, lightheadedness, or even fainting. The technical name is orthostatic hypotension — a drop in blood pressure when moving from lying or sitting to standing. It is one of the most common antipsychotic side effects and one of the most preventable causes of hospital-related falls.
Many antipsychotics block alpha-1 adrenergic receptors, which normally help blood vessels constrict on standing — the result is a transient blood pressure drop that resolves with practical measures and dose adjustments.
What it is
Orthostatic hypotension is defined as a drop of at least 20 mmHg systolic or 10 mmHg diastolic blood pressure within 3 minutes of standing. The brain is briefly starved of blood — hence dizziness, blurred vision, and the feeling of "greying out." Severe drops cause syncope (fainting), which can lead to falls and injury.
Why antipsychotics cause it
The main mechanism is alpha-1 adrenergic receptor blockade. Normally, when you stand, the sympathetic nervous system constricts blood vessels through alpha-1 receptors to maintain blood pressure. Antipsychotics that block these receptors blunt this response. Drugs with strong alpha-1 affinity cause more orthostatic hypotension.
Which medications are worst
- Highest risk: clozapine, chlorpromazine, quetiapine, iloperidone
- Moderate: olanzapine, risperidone, paliperidone, brexpiprazole
- Lowest: haloperidol, aripiprazole, lurasidone, ziprasidone, cariprazine
Iloperidone in particular requires a slow titration specifically to avoid orthostatic problems — its FDA labelling includes a specific titration schedule for this reason.
When it happens
Most commonly during initial titration and after dose increases. Also after long gaps in treatment when restarting. With clozapine, the first 1–2 weeks of titration are when orthostatic hypotension is most likely; this is part of why clozapine titration is deliberately slow.
Who is at greatest risk
- Older adults — autonomic responses are slower with age
- People taking blood pressure medications, particularly diuretics, alpha-blockers, or vasodilators
- People who are dehydrated, including from hot weather, recent illness, or alcohol
- People with diabetes, Parkinson's disease, or autonomic neuropathy
- People with low baseline blood pressure
How common
Reported rates vary widely:
- Clozapine: 9–21% during titration
- Quetiapine: 5–10%
- Iloperidone: up to 19% in some studies
- Olanzapine: 5%
- Haloperidol, aripiprazole, lurasidone: 1–3%
Real-world rates are higher than trial rates because trial populations exclude many higher-risk patients.
Symptoms to watch for
- Lightheadedness or dizziness on standing
- Blurred or "greyed out" vision briefly on standing
- Weakness or shakiness when first up
- Nausea
- Fainting (syncope)
- Falls — particularly worrying in older adults
What helps
1. Stand up slowly
Sit on the edge of the bed for a moment before standing. Then stand and pause. Then walk. This simple sequence can prevent most symptomatic episodes.
2. Hydrate
Drink water consistently through the day — at least 2 litres unless your prescriber has told you otherwise.
3. Add salt — within reason
Most people without hypertension or heart failure can safely add a bit of salt to the diet to help maintain blood volume. Discuss with your prescriber if you have any cardiovascular conditions.
4. Eat smaller meals
Large meals shift blood to the digestive system and can worsen orthostatic hypotension afterwards.
5. Avoid sudden changes
Don't stand up quickly from a hot bath or shower. Don't suddenly stand after sitting at a desk for hours. Don't drink alcohol and stand up rapidly.
6. Compression stockings
Knee-high or thigh-high compression stockings help prevent blood pooling in the legs and can be useful for persistent symptoms.
7. Slow the titration or split doses
If symptoms are dose-related, your prescriber can slow the titration, split the dose into smaller more frequent ones, or hold at a lower dose for longer.
8. Switch medications
If symptoms persist despite measures and dose adjustments, switching to a less alpha-blocking drug (aripiprazole, lurasidone) is reasonable.
Specific medical treatments
For severe persistent orthostatic hypotension that hasn't responded to the above, options sometimes used in coordination with a specialist include fludrocortisone (a mineralocorticoid that retains salt and water) and midodrine (an alpha agonist that constricts blood vessels). These are not first-line but can help in difficult cases.
When to call your prescriber
Any fainting episode. Falls related to dizziness. Lightheadedness that persists despite slowing the standing-up routine and hydrating. Symptoms after a recent dose increase or after starting a new medication that may interact (such as a blood pressure medication or an antidepressant).
The bottom line
Orthostatic hypotension is largely manageable. The most important thing is recognising it for what it is — a known medication effect, not a sign that something dramatic is wrong — and taking the simple practical steps that prevent falls. The patients who do best are those who treat it as a known issue from day one of treatment.
This article is for educational purposes only and is not medical advice, diagnosis, or treatment. Always consult a qualified mental health professional. If you or someone you know is in crisis, call or text 988 in the US, or your local emergency number.