From the Guidelines
Drugs that cause pupillary dilation (mydriasis) include anticholinergics, sympathomimetics, and certain antidepressants, antihistamines, and antipsychotics, as well as recreational drugs like MDMA and cocaine, which can disrupt the normal balance of the sympathetic and parasympathetic nervous systems that maintain pupil size. According to the most recent evidence from 1, patients with primary angle-closure disease should be warned that certain medicines, such as over-the-counter decongestants, cold and flu medications, allergy medications, and sleeping aids, as well as prescription psychoactive and motion-sickness medication, can cause pupil dilation and induce acute angle closure. Some key medications that can cause mydriasis include:
- Sympathomimetics like epinephrine, phenylephrine, and pseudoephedrine, which activate alpha-adrenergic receptors in the iris dilator muscle
- Anticholinergics such as atropine, scopolamine, cyclopentolate, and tropicamide, which block parasympathetic stimulation to the iris sphincter muscle
- Recreational drugs like MDMA (ecstasy), cocaine, amphetamines, LSD, and mescaline, which affect neurotransmitters and can cause mydriasis
- Antidepressants with anticholinergic properties, such as tricyclic antidepressants (amitriptyline, imipramine)
- Antihistamines with anticholinergic effects and certain antipsychotics, which can also produce mydriasis. As noted in 1, oral decongestants like pseudoephedrine and phenylephrine can cause mydriasis as a side effect, and patients with glaucoma should be cautious when using these medications. Additionally, 1 highlights the importance of considering the risks of anticholinergic medications, including mydriasis, in older adults, and recommends deprescribing these medications when possible to minimize adverse effects. Overall, it is essential to be aware of the potential for mydriasis when prescribing or using these medications, especially in patients with certain medical conditions or those who are at risk for acute angle closure.
From the FDA Drug Label
Pupillary dilation following topical administration of phenylephrine hydrochloride ophthalmic solution has been demonstrated in controlled clinical studies in adults and pediatric patients with different levels of iris pigmentation. Scopolamine can cause temporary dilation of the pupils resulting in blurred vision if it comes in contact with the eyes Mydriasis 4 0
The medications that cause mydriasis (pupillary dilation) are:
From the Research
Medications that Cause Mydriasis
The following medications have been associated with mydriasis (pupillary dilation):
- Anticholinergic drugs 4
- Antihistamines 4
- Antidepressant agents 4
- Central nervous system stimulants such as cocaine, methylphenidate, and amphetamines 4
- Adrenergic agents, either locally (phenylephrine drops, nasal ephedrine, or nebulized salbutamol) or systemically (epinephrine for anaphylactic shock) 5
- Drugs with anticholinergic effects including tropicamide and atropine drops 5
- Tri and tetracyclic antidepressants 5
- Cholinergic agents like pilocarpine 5
- Atropine 0.05% ophthalmic drops 6
- Atropine 1.0% pretreatment 7
Mechanisms of Mydriasis
Mydriasis can occur through various mechanisms, including:
- Pupillary block, which can be caused by adrenergic agents, anticholinergic agents, and cholinergic agents 5
- Ciliary body edema with anterior rotation of the iris-lens diaphragm, which can be caused by sulfa-based drugs such as acetazolamide, hydrochlorothiazide, cotrimoxazole, and topiramate 5
Clinical Implications
Mydriasis can be a significant side effect of certain medications, and clinicians should be aware of the potential for mydriasis when prescribing these medications 8, 4, 5. In some cases, mydriasis can lead to acute angle closure glaucoma, which is a potentially blinding condition 5.