You’ve packed your gear, checked your tank, and you’re ready to hit the water—except for one thing: Your nose is stuffed, and that little pill looks like an easy fix.

But before you take that decongestant, there’s something you should know as a diver. What looks like a harmless fix on land can turn into a dangerous risk underwater.

In this article, we dive deep into why decongestants and scuba diving don’t mix, the hidden risks they pose, and the safer alternatives that let you breathe easy—above and below the surface.

Using Decongestant When Scuba Diving

Decongestants might help for a short time, but they can cause trouble when you’re scuba diving.

Decongestant nasal sprays can lead to rebound congestion Once they stop working. If the decongestant stops working during the dive, it could lead to a reverse block, leading to barotrauma (reverse squeeze) while ascending. Prolonged use (more than three days) can lead to persistent rebound congestion which may last from weeks to months.

Decongestants may slightly stimulate the nervous system, causing symptoms like nervousness, dizziness, excitability, weakness, restlessness, and a forceful or rapid heartbeat. Before you dive with any drug, it is recommended to experience taking it on land.

Decongestants may increase the risk of oxygen toxicity. A 2013 rat study by DAN and University of South Florida (USF) found that normal pseudoephedrine doses didn’t raise seizure risk, but responses varied widely between individuals. The researchers advise not to exceed the daily dose of pseudoephedrine before scuba diving, especially in case of deep diving or using gases other than normal air. Double check the active ingredients in any medications you use to ensure that you take the recommended dose!

Why Decongestants and Diving Don’t Mix

OTC drugs, like decongestants, may seem harmless but can cause side effects—some risky for divers. Taking them before a dive, especially with cold symptoms, can be dangerous and result in some problems, such as:

Nervousness and Jitters

Decongestants can make you feel jittery and nervous. People that experience nervousness and the jitters have a variable air consumption when compared to normal divers, and they may even find themselves shallow breathing, which can result in hyperventilation.

Difficulty Sleeping

A diver should have the ability to concentrate and think clearly. From the fact that these drugs are known for their sleeplessness activity, Lack of proper rest can leave a diver feeling groggy and fatigued.

This kind of fatigue has a bad effect on their thinking process. Divers depend on the ability to have a rapid response and think clearly to prevent injuries to themselves and others.

Increase Heart Rate

Decongestants can significantly raise heart rate. When diving, the heart rate increases a bit naturally. They also increase the heart rate, so having the two factors can lead to serious health implications. Increased heart rate in addition to shortness of breath can be a deadly combination beneath the waves.

Decongestants have a great job in clearing the nasal passages. Warning labels rarely mention SCUBA diving, even when the drugs may be unsafe for it.

But in general, when diving, it isn’t recommended to take a decongestant, and instead of that, postpone the dive until you are ok.

Since every person has a different response to drugs, it is crucial to understand how your body reacts to decongestants before attempting to dive or participate in any activity underwater.

Recommended Alternatives for Decongestants When Scuba Diving

You have many ways to deal with congestion and enjoy your dive. For example, you can choose one of the effective equalization methods.

Most scuba divers clear their ears by pinching their nose and blowing lightly. However, other techniques may be more effective for you. These include Lowry, Toynbee, and Edmonds maneuvers.

If you want to know more about these techniques, Read our article with descriptions of each of these equalization methods available online.

Humidifiers, warm compress or nasal irrigation devices like a neti pot are considered another alternative to decongestants. These methods help loosen and clear out mucus.

If you suffer from frequent allergies or congestion, consider speaking with a doctor who may recommend antihistamines or steroids to control your symptoms. As with any medication, make sure you know how they affect you before you go diving.

Diving is thrilling, so it’s natural not to let a cold or allergies get in the way. However, be careful about the type of medications you are going to take before diving. If you can’t equalize or feel frequent pain or have nosebleeds when diving, call the nearest dive center, see your doctor, or look for an ear, nose and throat specialist (ENT/otolaryngologist) for any added advice.