Cinnarizine Overdose: Signs, Symptoms, First Aid, and Treatment Guide

If someone takes too much cinnarizine, the clock starts ticking. The drug can make people very sleepy, confused, wobbly on their feet, and in higher amounts it can slow breathing and drop blood pressure. This guide shows you the red flags to watch for, what to do in the first 10 minutes, what doctors will do in the ER, and how to prevent it from happening again. Expect clear first-aid steps you can follow, a quick decision path, and straight answers to common questions.

• Most overdoses cause heavy drowsiness, confusion, unsteady walking, fast heart rate, low blood pressure, and sometimes muscle stiffness or tremor.
• If there’s severe drowsiness, trouble breathing, seizures, collapse, or the person is a child, call emergency services now. Then call your local poison control center for dosing advice.
• Don’t make them vomit. Keep them awake if safe, on their side if drowsy, and take away remaining tablets.
• In hospital, care is supportive: airway, fluids, heart monitoring, activated charcoal if early, and meds for seizures or muscle spasms.
• Prevention is simple: clear labels, avoid mixing with alcohol or sedatives, use a pill organizer, and lock meds away from kids.

What a Cinnarizine Overdose Is (and Why It Happens)

Cinnarizine is a first-generation antihistamine with extra actions that steady the inner ear. It’s used for motion sickness and vertigo in many countries. Typical adult tablets are 25 mg (sometimes combined with dimenhydrinate in certain brands). It can cause drowsiness at normal doses. In larger amounts, those sedative effects go up fast.

Why do overdoses happen? Most are accidental: taking an extra dose on a long trip, mixing brands (for example, a plain cinnarizine tablet plus a combo product that already contains it), or chasing nausea with multiple meds. Sometimes it’s intentional. Alcohol and other sedatives (benzodiazepines, opioids, sleep meds) make the sedation stronger and riskier.

Who’s at higher risk of bad outcomes?

• Children-they can get very sick from small amounts compared to adults.
• Older adults-more sensitive to confusion, falls, and blood pressure drops.
• People with Parkinson’s disease-cinnarizine can worsen movement symptoms or trigger acute dystonia.
• People on multiple sedatives or with liver problems-drug effects can last longer and hit harder.

There’s no specific antidote to a cinnarizine overdose. The good news: with prompt first aid and medical care, people usually do well. That’s why recognizing the signs (next section) and acting quickly matter.

Signs and Symptoms: What to Look For (and When)

Symptoms usually start within a couple of hours of swallowing extra tablets. The intensity depends on the dose, the person, and what else was taken (especially alcohol or other sedatives).

Typical timeline and features:

• 0-2 hours: drowsiness, dizziness, dry mouth, blurred vision, nausea. Kids may become agitated instead of sleepy.
• 2-6 hours: confusion, slurred speech, unsteady gait (ataxia), fast heart rate, low blood pressure, vomiting, urinary retention. Movement problems can show up: stiff neck, jaw clenching, oculogyric crisis (eyes forced upward), tremor.
• Severe cases: very slow breathing, very low blood pressure, seizures (uncommon), delirium, or coma. Abnormal heart rhythms are possible but not typical.

How to tell if it’s getting dangerous:

• You can’t keep them awake or they stop responding.
• They’re breathing slow, shallow, or irregular.
• They faint, seize, or can’t stand without help.
• There’s chest pain, a very fast or very slow heartbeat, or severe headache.

Important look‑alikes: Severe unsteadiness, slurred speech, or confusion can mimic stroke. If one side is weak, the face droops on one side, or speech is garbled in bursts, treat it as a stroke and call emergency services immediately.

Sources for pharmacology and overdose features: UK BNF, EMA Summary of Product Characteristics (cinnarizine-containing products), and national poisons center guidance (NPIS ToxBase, last updates through 2024; AACT/AAPCC antihistamine poisoning guidance).

What To Do Right Now: First Aid and a Simple Decision Path

If you think someone took too much, act now. Here’s a simple playbook.

1. Check responsiveness and breathing. If they’re not waking to voice or touch, or breathing is slow or irregular, call emergency services immediately.
2. Remove the source. Take away any remaining tablets or blister packs.
3. Don’t induce vomiting. It doesn’t help and can cause choking.
4. Call your poison control center. They’ll ask age, weight, exact product, strength, how many tablets, and when. If you’re not sure, save the packaging and count what’s left.
5. Position. If drowsy but breathing, lay them on their side (recovery position). Loosen tight clothing.
6. Keep it calm. No alcohol, no driving, no new meds “to wake up.” Small sips of water are fine if they’re fully awake.
7. Watch for the next 6-8 hours. Look for worsening drowsiness, confusion, unsteady gait, stiff muscles, or shaking. If symptoms escalate, head to the ER.

Quick decision path you can follow:

• If the person is a child, pregnant, very elderly, has Parkinson’s disease, or took the drug with alcohol/other sedatives: call poison control now, even if they look okay.
• If there’s severe drowsiness, a fall, chest pain, seizures, or breathing trouble: call emergency services first, then poison control.
• If an adult took a modest extra dose (for example, one extra 25 mg tablet), has no symptoms after 4-6 hours, and didn’t mix with sedatives: poison control may suggest home observation. Still call for tailored advice.

What to tell poison control (keep this checklist handy):

• Age, weight, medical problems (especially Parkinson’s, heart disease, liver disease).
• Product name and strength (plain cinnarizine vs a combination tablet).
• How many tablets were taken, and at what time.
• What else was taken: alcohol, sleep meds, opioids, antihistamines.
• Current symptoms and when they started.

What not to do:

• Don’t give coffee or energy drinks to “counter” sedation. It won’t fix it.
• Don’t use home remedies like salt water to induce vomiting.
• Don’t let a very drowsy person “sleep it off” unwatched. Check them often, and be ready to call for help.

What Hospitals Do: Tests, Treatments, and What to Expect

In the ER, care is supportive and focused on keeping vital functions safe while the drug wears off. There’s no magic reversal pill.

Common steps:

• Assessment and monitoring: vital signs, oxygen levels, blood glucose (to rule out low sugar), and a heart tracing (ECG). Expect observation for at least 6 hours, longer if symptoms are significant or mixed overdose is suspected.
• Activated charcoal: a single dose may be given if arrival is within a few hours of ingestion and the person can protect their airway. It reduces absorption. It’s not given at home.
• Fluids and blood pressure support: IV fluids if blood pressure is low. If needed, vasopressors are used, guided by monitors.
• Seizure control: benzodiazepines (like lorazepam) are first-line. Fast, effective, safe.
• Movement problems (acute dystonia, oculogyric crisis): anticholinergic agents (benztropine, biperiden) or IV/IM diphenhydramine can reverse symptoms quickly.
• Agitation or delirium: calm environment, benzodiazepines in small doses. Avoid heavy dopamine-blocking drugs if possible, since cinnarizine already has antidopaminergic effects.
• Heart rhythm issues: continuous ECG. Serious arrhythmias are uncommon with cinnarizine alone, but mixed overdoses change the picture.

What usually isn’t helpful:

• Dialysis or hemoperfusion. Cinnarizine is highly protein-bound and distributes widely, so these methods don’t clear it well.
• Whole-bowel irrigation. Not routine unless a large sustained-release co‑ingestion is suspected (rare with cinnarizine).
• Physostigmine. Not standard and carries risks; reserved for very specific anticholinergic delirium cases under toxicology guidance.

Expected course: Most people improve within 12-24 hours. Movement symptoms can lag and may need targeted treatment. After an intentional overdose, a mental health assessment is standard before discharge.

Evidence and guidance: UK National Poisons Information Service (ToxBase), British National Formulary (latest edition), EMA product information for cinnarizine-containing medicines, and position statements from the American Association of Poison Control Centers and the American Academy of Clinical Toxicology on sedating antihistamine poisonings.

Prevention, Pitfalls, and Special Situations

Simple habits prevent most mishaps. Use these rules of thumb:

• One product at a time. If you switch brands, check if the new one already contains cinnarizine.
• Mark your doses. Use a pill organizer or set phone reminders, especially on travel days.
• No alcohol or extra sedatives. Mixing increases the risk of dangerous sleepiness and breathing problems.
• Lock meds up. Keep tablets in child-resistant containers and out of sight and reach.
• Driving and machinery: skip both until you know how cinnarizine affects you-and never after an extra dose.

Special groups:

• Children: Even a few tablets can be serious. Don’t wait for symptoms-call for advice right away.
• Older adults: Higher risk of confusion, falls, and low blood pressure. Lower starting doses and tighter monitoring are wise.
• Parkinson’s disease: Cinnarizine can worsen symptoms or trigger movement disorders. Avoid unless a specialist says otherwise; treat dystonia promptly if it happens.
• Pregnancy and breastfeeding: If an overdose occurs, seek medical advice promptly. ER teams will choose treatments that are pregnancy- and lactation-safe.

Medication mix-ups to watch for:

• Combination tablets: In some markets, tablets pair cinnarizine with dimenhydrinate. Taking those plus plain cinnarizine doubles the dose.
• Other antihistamines: Adding meclizine, diphenhydramine, promethazine, or doxylamine ramps up sedation and anticholinergic side effects.
• Sleep meds, opioids, benzodiazepines, alcohol: Strong additive sedation; higher risk of airway problems.

Mini‑FAQ

• How much is “too much”? It depends on body weight, sensitivity, and what else was taken. As a rough guide, anything more than your total daily dose at once deserves a call to poison control. In kids, any unknown amount needs evaluation.
• Can I sleep it off? Not safely if you’re very drowsy. Someone should check on you often. If you’re hard to wake or breathing seems slow or shallow, that’s an emergency.
• Should I make myself throw up? No. It’s risky and doesn’t help. Charcoal, if appropriate, belongs in a monitored setting.
• How long until I feel normal? Many people feel better within a day. Movement issues (stiff neck, jaw, eye deviations) can last longer but are treatable.
• Will this harm my heart? Serious rhythm problems are not common with cinnarizine alone, but mixed overdoses can change the picture. ER teams will check an ECG to be safe.
• Is there an antidote? No. Care is supportive and symptom‑based, which works well in most cases.

Next steps and troubleshooting by scenario

• Adult took one extra 25 mg tablet, no other meds, feels fine: Note the time, skip the next dose, hydrate, avoid driving and alcohol, and call poison control for tailored advice. If you stay symptom‑free after 6 hours, risk is low.
• Child may have swallowed unknown tablets: Count the pack, estimate the max possible number missing, and call poison control now. Head to the ER if advised, even if the child looks okay.
• Mixed with alcohol or sleep pills: Treat as higher risk. Don’t wait for symptoms-call now. Arrange safe supervision and be prepared to go to the ER.
• Elderly family member feels dizzy and confused after dosing: Sit or lay them down, check blood pressure if you can, and call for advice. Falls and low BP are the big risks; medical review is sensible.
• Person with Parkinson’s has jaw clenching or eye deviation: This may be acute dystonia. Seek urgent care; it’s very treatable, but they need the right medication.
• No poison center access (remote area): Prioritize airway and breathing. If severe symptoms appear, activate emergency services. If mild, observe closely for at least 8 hours, avoid any sedatives, and keep the person on their side if sleepy.

Credibility note: This guide draws on recognized toxicology and prescribing references: UK BNF, EMA SmPC for cinnarizine‑containing products, UK NPIS ToxBase guidance (2024 updates), and position statements from the American Academy of Clinical Toxicology and the American Association of Poison Control Centers on sedating antihistamine poisonings. Local guidance varies; follow your regional poison center or emergency services.