Understanding Patient Safety: What are the contraindications of Cyclizine?

October 12, 2025 •

4 min read

Cyclizine, an antihistamine discovered in 1947, is commonly used to prevent and treat nausea and vomiting [1.6.4]. Understanding what are the contraindications of Cyclizine is crucial for its safe use, as it is not suitable for everyone [1.2.2].

Quick Summary

A detailed review of Cyclizine's contraindications. The key reasons to avoid this medication include certain medical conditions like glaucoma, liver disease, and prostate issues, plus interactions with other drugs.

Key Points

Absolute Contraindications: Do not take Cyclizine if you have a known allergy to it or if you have consumed alcohol [1.2.7, 1.5.3].
Anticholinergic Effects: Use with caution in patients with glaucoma, urinary retention, enlarged prostate, or obstructive bowel disease [1.2.2, 1.2.8].
Cardiovascular and Liver Health: Patients with severe heart failure or significant liver problems should consult a doctor before use [1.2.2, 1.3.5].
CNS Depressant Interactions: Avoid combining with alcohol, opioids, sleeping pills, or other sedatives, as this can cause dangerous levels of drowsiness [1.4.6, 1.4.7].
Special Populations: The elderly may need a lower dose, and its use in pregnancy or while breastfeeding requires medical advice [1.3.5, 1.2.8].
Impaired Abilities: Cyclizine can cause drowsiness and blurred vision; do not drive or operate machinery until you know how it affects you [1.5.1].
Medical Consultation is Key: Always disclose your full medical history and all medications you are taking with your doctor or pharmacist before starting cyclizine [1.3.2].

Introduction to Cyclizine

Cyclizine is an antihistamine medication belonging to the piperazine derivative class [1.6.4, 1.2.5]. Its primary function is to block histamine H1-receptors in the brain, which helps to alleviate symptoms of nausea, vomiting, and dizziness [1.6.2, 1.6.4]. It is commonly used for motion sickness, vertigo, and nausea following surgery or caused by other medications [1.5.3, 1.5.6]. The medication works by affecting the vestibular system and the chemoreceptor trigger zone in the brain, and it also possesses anticholinergic (antimuscarinic) properties [1.6.4, 1.6.6]. While effective for many, its use is restricted in certain populations and conditions due to a range of potential adverse effects.

Absolute and Relative Contraindications

A contraindication is a specific situation in which a drug should not be used because it may be harmful to the person. It's essential to distinguish between absolute contraindications (situations where the drug must not be used) and relative contraindications (where caution is advised, and the benefits must outweigh the risks).

Absolute Contraindications

Hypersensitivity: A known allergy to cyclizine or any of its ingredients is an absolute contraindication. Allergic reactions can range from skin rashes to severe anaphylaxis, including swelling of the face, lips, or tongue, and difficulty breathing [1.2.2, 1.5.3].
Acute Alcohol Intoxication: Cyclizine should not be taken with alcohol. Its anti-vomiting properties can mask and potentially increase the toxicity of alcohol [1.2.7, 1.3.6].
Children Under 6: Cyclizine tablets are not recommended for use in children under the age of six [1.5.3, 1.3.4].

Conditions Requiring Precaution (Relative Contraindications)

Due to its anticholinergic effects, cyclizine must be used with caution in individuals with certain pre-existing conditions [1.2.8]. A healthcare provider should be consulted if you have any of the following:

Glaucoma: Cyclizine can increase pressure within the eye, potentially worsening this condition [1.2.2, 1.3.5].
Urinary Retention & Prostate Enlargement: Men with an enlarged prostate gland may find it more difficult to pass urine, a side effect that cyclizine can exacerbate [1.2.2, 1.3.1].
Obstructive Bowel Conditions: The medication can worsen issues in patients with conditions like Crohn's disease or diverticulitis that could lead to bowel obstruction [1.2.2, 1.2.3].
Severe Liver Disease: Since cyclizine is metabolized by the liver, severe hepatic impairment can affect how the drug is processed [1.2.2, 1.2.5].
Epilepsy: Individuals with epilepsy or other conditions that cause seizures should use cyclizine cautiously as it may affect seizure thresholds [1.2.2, 1.2.3].
Cardiovascular Disease: In patients with severe heart failure, cyclizine can sometimes cause a fall in cardiac output associated with an increased heart rate [1.2.2, 1.6.9].
Porphyria: This rare inherited blood disorder is another condition where cyclizine should be avoided [1.2.2, 1.2.3].
Phaeochromocytoma: A rare tumor of the adrenal glands [1.2.2, 1.2.8].
Breathing Problems: Patients with conditions like asthma, emphysema, or chronic bronchitis should consult a doctor before use [1.3.1].

Significant Drug Interactions

Cyclizine's effects can be dangerously amplified when combined with other substances that depress the central nervous system (CNS). It's crucial to inform your doctor about all medications you are taking.

CNS Depressants: Combining cyclizine with alcohol, sleeping pills, opioid painkillers (like hydrocodone or morphine), tranquilizers, or medications for anxiety and depression can lead to increased drowsiness, sedation, and impaired coordination [1.3.2, 1.4.6, 1.4.8].
Anticholinergic Drugs: Taking other medications with anticholinergic properties (used for various conditions including depression and bladder control) can intensify side effects like dry mouth, blurred vision, and urinary retention [1.2.1, 1.4.5].
Monoamine Oxidase Inhibitors (MAOIs): Antidepressants like phenelzine can interact with cyclizine [1.4.5].
QTc-Prolonging Drugs: Cyclizine can interact with numerous drugs that affect heart rhythm, increasing the risk of QTc prolongation, a potentially serious heart rhythm change. Examples include certain antibiotics (azithromycin), antiarrhythmics (amiodarone), and antipsychotics [1.4.1].

Comparison of Anticholinergic Side Effects


Feature	Cyclizine	Scopolamine (another motion sickness drug)
Primary Use	Nausea, vomiting, motion sickness [1.5.3]	Motion sickness, postoperative nausea [1.4.7]
Common Side Effects	Drowsiness, dry mouth, blurred vision [1.3.7]	Dry mouth, drowsiness, blurred vision
Anticholinergic Potency	Moderate	High
CNS Effects	Can cause drowsiness, confusion, dizziness [1.2.4]	Can cause significant drowsiness, disorientation
Risk in Glaucoma	Caution required [1.2.2]	Contraindicated in angle-closure glaucoma

Warnings and Special Populations

Pregnancy and Breastfeeding: While sometimes used for severe morning sickness, manufacturers generally advise that cyclizine be avoided during pregnancy unless prescribed by a doctor, as definitive human data is limited [1.2.8, 1.5.5]. The drug is excreted in human milk, and its use is not recommended for breastfeeding women [1.2.8].
Elderly Patients: Individuals over 65 may have a stronger reaction to cyclizine and may require a smaller dose. They are also more susceptible to side effects like confusion, dizziness, and impairment in judgment [1.3.5, 1.2.3].
Driving and Operating Machinery: Due to common side effects like drowsiness, blurred vision, and impaired coordination, you should not drive or operate heavy machinery until you know how cyclizine affects you [1.5.1].

Conclusion

Cyclizine is an effective anti-sickness medication, but its use is governed by important contraindications and precautions. Its anticholinergic properties are the primary reason for caution in patients with glaucoma, urinary retention, and certain heart conditions. The most significant risk comes from its additive effects when combined with other CNS depressants like alcohol or opioids. Always consult a healthcare professional or pharmacist before taking cyclizine to ensure it is safe for you, especially if you have pre-existing medical conditions or are taking other medications [1.2.2, 1.3.2].

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional before starting or stopping any medication.

Authoritative Link: Cyclizine - NHS

Frequently Asked Questions

You should not take cyclizine if you've had an allergic reaction to it, if you have consumed alcohol, or if you are giving it to a child under 6 [1.2.2, 1.2.7, 1.5.3]. People with certain conditions like glaucoma, severe liver problems, or an enlarged prostate should consult a doctor first [1.2.2].

No, you should not drink alcohol while taking cyclizine. The combination can increase the toxicity of alcohol and worsen side effects like drowsiness and dizziness [1.2.7, 1.5.1].

You should talk to your doctor before taking cyclizine if you have glaucoma. The medication can increase pressure in the eye, which may worsen the condition [1.2.2, 1.3.5].

The most significant interactions are with other central nervous system depressants, such as alcohol, opioid painkillers, and sedatives, which can cause extreme drowsiness [1.4.6]. It can also interact with other anticholinergic drugs and certain antidepressants [1.2.1].

You should not drive or operate machinery after taking cyclizine until you know how it affects you. It commonly causes drowsiness, dizziness, and blurred vision, which can impair your ability to drive safely [1.5.1].

Elderly individuals (over 65) may have a stronger reaction to cyclizine and are more susceptible to side effects like confusion and dizziness. A lower dose may be necessary, and it should be used under medical guidance [1.3.5, 1.2.3].

If you have painful or difficult urination, or are passing little to no urine, you should stop taking cyclizine and call your doctor at once, as this can be a serious side effect [1.2.1].