What Happens If You Take Too Much Ketotifen? An Overdose Guide

October 9, 2025 •

3 min read

While no fatal overdoses from ketotifen have been reported, taking too much can lead to significant symptoms [1.2.2]. Understanding what happens if you take too much ketotifen is crucial for anyone using this medication for allergies or asthma.

Quick Summary

Taking an excessive amount of ketotifen can cause symptoms like severe drowsiness, confusion, disorientation, fast heart rate, and low blood pressure. In children, it may cause hyperexcitability or convulsions.

Key Points

Overdose Symptoms: The primary signs of taking too much ketotifen are severe drowsiness, confusion, disorientation, fast heart rate (tachycardia), and low blood pressure (hypotension) [1.8.2].
Pediatric Risks: Children may experience different overdose symptoms, including hyperexcitability and convulsions, in addition to sedation [1.3.3].
No Fatalities Reported: Although overdoses up to 120 mg have been documented, there are no reported deaths from taking too much ketotifen alone [1.2.2, 1.6.5].
Immediate Action: If a ketotifen overdose is suspected, call a poison control center (1-800-222-1222 in the US) immediately. Call 911 for severe symptoms like seizures or loss of consciousness [1.3.1].
Medical Treatment: Hospital treatment involves supportive care, monitoring vital signs, and potentially administering activated charcoal to limit drug absorption [1.8.2].
Drug Interactions: The risk of overdose symptoms increases when ketotifen is combined with alcohol, opioids, sedatives, or other antihistamines [1.3.1].
Dual Action: Ketotifen works as both an antihistamine and a mast cell stabilizer, which is why it's used for both eye allergies and preventing asthma attacks [1.4.3].

Understanding Ketotifen and Its Uses

Ketotifen is a medication with a dual mechanism of action: it is an H1-antihistamine and a mast cell stabilizer [1.4.3, 1.4.5]. This means it not only blocks histamine, a substance that causes allergic symptoms, but also prevents immune cells called mast cells from releasing inflammatory mediators [1.4.4]. This makes it effective for various conditions.

Primarily, ketotifen is used in several forms:

Ophthalmic (Eye Drops): In the U.S., it is widely available over-the-counter as eye drops (e.g., Zaditor, Alaway) to relieve itching associated with allergic conjunctivitis [1.4.2].
Oral (Capsules, Syrup): Oral ketotifen is used as a long-term maintenance treatment to prevent or reduce the severity of asthma attacks, especially in children [1.4.1]. It is not effective for acute asthma attacks [1.4.1]. It's also prescribed for mast cell activation syndrome (MCAS), chronic urticaria, and other allergic conditions [1.4.3]. In the United States, oral forms are not commercially available and must be prepared by a compounding pharmacy [1.4.3].

Standard Dosages

Dosage depends on the form and the patient's age. For adults and children over 3, a common oral dose is 1 mg twice daily [1.5.3]. For children aged 6 months to 3 years, the dose is typically 0.5 mg twice daily [1.5.3]. To minimize side effects like drowsiness, a doctor may start with a lower dose and gradually increase it [1.3.1].

What Happens If You Take Too Much Ketotifen?

While clinical data shows a strong safety profile, with no serious symptoms reported in ingestions of up to 20 mg and no reported fatal overdoses, taking a significantly higher dose can lead to acute overdose symptoms [1.3.2, 1.2.2]. Overdoses of up to 120 mg have been reported [1.6.5].

Symptoms of an Overdose

The main symptoms of a ketotifen overdose primarily affect the central nervous system [1.8.2].

Common and Severe Symptoms Include:

Drowsiness to severe sedation [1.8.2]
Confusion and disorientation [1.8.2]
Tachycardia (fast heart rate) [1.3.3]
Hypotension (low blood pressure) [1.3.3]
Reversible coma [1.6.5]

In children, the symptoms can differ slightly and may include hyperexcitability, irritability, and convulsions [1.8.2, 1.3.3].

Immediate Steps for a Suspected Overdose

If you suspect someone has taken too much ketotifen, it is crucial to act quickly.

Call for Emergency Help: If the person displays serious symptoms like passing out, seizures, or trouble breathing, call 911 immediately [1.3.1].
Contact Poison Control: For any suspected overdose, call a poison control center right away. US residents can call 1-800-222-1222 [1.3.1].
Do Not Induce Vomiting: Unless specifically instructed by a medical professional, do not try to make the person vomit.

Medical Treatment for Overdose

Treatment for a ketotifen overdose is primarily symptomatic and supportive [1.8.2].

Stomach Decontamination: If the ingestion was recent, healthcare providers may consider gastric lavage (stomach pumping) or administering activated charcoal to absorb the drug [1.8.2].
Monitoring: Vital signs, especially the cardiovascular system, will be monitored closely [1.8.2].
Symptomatic Treatment: If convulsions or severe excitation occurs, short-acting barbiturates or benzodiazepines may be given [1.8.2]. Physostigmine may be used to counteract severe anticholinergic effects [1.2.2].

Risk Factors and Interactions

The risk of adverse effects increases when ketotifen is taken with other substances that cause drowsiness. This includes:

Alcohol [1.3.1]
Opioid pain relievers (e.g., codeine) [1.3.1]
Sleep or anxiety medications (e.g., alprazolam, zolpidem) [1.3.1]
Other antihistamines (e.g., diphenhydramine) [1.3.1]

Ketotifen can also lower the seizure threshold, so it should be used with caution in patients with a history of epilepsy [1.3.4].

Comparison with Other Antihistamines


Feature	Ketotifen (Oral)	Diphenhydramine (Benadryl)	Cetirizine (Zyrtec)
Generation	Often classified as a second-generation, but has sedating effects similar to first-generation [1.4.4].	First-Generation	Second-Generation
Primary Mechanism	H1-antihistamine and mast cell stabilizer [1.4.3].	H1-antihistamine [1.3.6].	H1-antihistamine [1.7.5].
Sedation Level	Common, but often decreases with continued use [1.3.4, 1.7.1].	High [1.3.6].	Low to non-sedating for most users [1.3.6].
Overdose Symptoms	Drowsiness, confusion, tachycardia, hypotension [1.3.3].	Drowsiness, dizziness, fast heart rate, dilated pupils [1.3.6].	Primarily drowsiness, but less severe CNS effects than first-gen [1.3.6].
Common Side Effects	Drowsiness, weight gain, dry mouth [1.7.1].	Drowsiness, dry mouth, dizziness [1.7.3].	Drowsiness, fatigue, dry mouth [1.7.5].

Conclusion

While ketotifen is a generally safe and effective medication for managing allergies and asthma, taking too much can lead to serious health issues. The most prominent effects of an overdose are severe drowsiness, confusion, and changes in heart rate and blood pressure. It is essential to use this medication only as prescribed and to be aware of its interactions with other substances that cause sedation. In any case of a suspected overdose, seeking immediate medical attention is critical for a safe outcome.

For more information on medication safety, consult resources like the FDA's drug information portal.

Frequently Asked Questions

There is no exact toxic dose defined, but ingestions of up to 20 mg have shown no serious symptoms, while overdoses have been reported with amounts as high as 120 mg. Symptoms of acute overdose include severe sedation, confusion, and cardiovascular changes [1.8.5, 1.6.5].

No fatal overdoses associated with ketotifen have been described in clinical reports [1.2.2]. However, an overdose can cause serious symptoms requiring immediate medical attention.

The earliest and most common signs are significant drowsiness, confusion, and disorientation [1.8.2]. You might also experience a rapid heartbeat or dizziness.

Yes. While adults primarily experience sedation, children can paradoxically become hyperexcitable or have convulsions [1.8.2].

If you miss a dose, you should not double the next one [1.3.1]. A single accidental double dose is unlikely to cause severe issues in an adult but may increase side effects like drowsiness. If you are concerned or experience unusual symptoms, contact your doctor or a poison control center.

No, you should limit or avoid alcoholic beverages. Alcohol can intensify the drowsiness and dizziness caused by ketotifen [1.3.1].

Treatment is mainly supportive. It may include administering activated charcoal to prevent further absorption of the drug and monitoring the person's cardiovascular system. In cases of severe excitation or convulsions, benzodiazepines may be used [1.8.2].