During cold and allergy season, many people turn to nasal decongestants to help them breathe better. The short-term effects are consistent with brain health, as they can improve breathing and sleep quality. But, with reports linking the use of these over-the-counter remedies to cases of strokes [1], are there possible long-term negative impacts to the brain from these cold medicines?
There are two major classes of over-the-counter nasal decongestants [2]. One class includes pseudoephedrine, which is commonly found in cold medicines in the form of pills or syrups. The other class includes oxymetazoline, which is a main active ingredient in nasal sprays. Both classes of drugs activate the sympathetic arm of the autonomic nervous system. This system activates the ‘fight or flight’ response. One of the major effects of this system is the constriction of blood vessels, which is why these drugs work well as nasal decongestants [3]. Constriction of the blood vessels in the nose opens up the nasal passage, which makes it easier for air to flow in and out.
While temporarily reducing blood flow to a stuffy nose may improve breathing quality, simultaneously reducing blood flow to other parts of the body, such as the brain, is not necessarily a good thing. Just as getting frightened can make the heart race, these ‘fight or flight’ response-activating drugs can also increase blood pressure and heart rate [3]. This is why these medicines have been associated with cases of heart attack and stroke [1; 4].
An analysis of studies including over a thousand people that used orally administered nasal decongestants found that, on average, the increases in heart rate (2.8 beats per minute) and blood pressure (1 mmHg) were not high enough to be clinically relevant in most people [3]. Consistent with this, a recent study including nearly 3,000 people found that the use of nasal decongestants was not significantly associated with heart attack or stroke in people without underlying risk factors [2].
These studies indicate that while the risks are very low for otherwise healthy people, there are certain conditions which can make someone more susceptible to these severe side effects. This includes people with a history of cardiovascular disease, as well as those with conditions that can lead to the dysfunction of the autonomic nervous system, such as diabetes, neurodegenerative disease, and some autoimmune conditions [3; 4]. When used at extremely high doses, these drugs can potentially reach the brain, leading to symptoms of anxiety or paranoia in vulnerable individuals with a history of psychiatric illness [5].
The risk for these effects arises when the drugs are present throughout the body at high concentrations [6]. This occurs when the drug gets into the bloodstream and can circulate around the body. The way a drug is taken affects how readily it gets into the blood. Nasal decongestants taken orally get into the blood readily, while those administered locally to the nose are much less likely to get in the blood and have effects in other parts of the body. Consistent with this, there are more reported cases of heart attacks and strokes stemming from the use of nasal decongestants taken orally in pills and syrups than from nasal sprays [1; 4].
The dose appears to be the major factor influencing the risk for these effects on the heart and brain. This includes the amount taken at a time as well as the frequency of use. It is recommended that nasal decongestants be used up to two times per day for no more than three days. Chronic use can damage the nasal tissue in a manner than increases the risk for infections and leads to rebound congestion [7; 8].
Overall, when used in accordance with recommended guidelines, nasal decongestants are safe for most people. Individuals with conditions that may increase their risk for severe side effects should consult their doctor before using this type of medicine.
Betsy Mills, PhD, is a member of the ADDF's Aging and Alzheimer's Prevention program. She critically evaluates the scientific evidence regarding prospective therapies to promote brain health and/or prevent Alzheimer's disease, and contributes to CognitiveVitality.org. Dr. Mills came to the ADDF from the University of Michigan, where she served as the grant writing manager for a clinical laboratory specializing in neuroautoimmune diseases. She also completed a Postdoctoral fellowship at the University of Michigan, where she worked to uncover genes that could promote retina regeneration. She earned her doctorate in neuroscience at Johns Hopkins University School of Medicine, where she studied the role of glial cells in the optic nerve, and their contribution to neurodegeneration in glaucoma. She obtained her bachelor's degree in biology from the College of the Holy Cross. Dr. Mills has a strong passion for community outreach, and has served as program presenter with the Michigan Great Lakes Chapter of the Alzheimer's Association to promote dementia awareness.
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