The purpose of this research is to study whether the use of pseudoephedrine can help prevent middle ear trauma during HBOT. Pseudoephedrine is an approved drug that is used for temporary relief of nasal or sinus pain and pressure.

Subjects will be asked to take a pill (pseudoephedrine or placebo) between 45 and 120 minutes before hyperbaric oxygen therapy. Subjects' ears will be examined before and after therapy and be asked to assess ear pain. There will be no further tests or procedures after completion of therapy session and ear examinations.

Inclusion Criteria:

• New patient requiring HBOT (either inpatient or outpatient)
• Age greater than or equal to 18 years and less than 80 years
• Fluent in English
• Full decision capacity
• Able and medically cleared to swallow a pill

Exclusion Criteria:

• Enrollment would delay hyperbaric therapy more than 30 minutes in patients with emergent indications (example: Central Retinal Arterial Occlusion, Carbon Monoxide, Air Gas Embolism)
• Contraindication to pseudoephedrine (monoamine oxidase inhibitors (MAOI) use, pregnancy, glaucoma, heart disease, allergy to drug class)
• Systolic Blood Pressure >160
• Diastolic Blood Pressure > 90
• Heart Rate >100
• Decongestant/antihistamine/pseudoephedrine/nasal steroid/oxymetazoline use within 12 hours.
• Prisoner
• Intubated
• Unable to swallow oral medications

double-blind placebo control