Key messages
– We found no evidence that taking oral decongestants (medicine taken by mouth to relieve a stuffy nose) daily for a week or more changes blood pressure or heart rate or causes people to stop taking them due to unwanted effects.
– There were only a few studies, and they were not well designed. More well-conducted studies are needed.
– Given that oral decongestants are sometimes taken daily for weeks or months, and have the potential to increase blood pressure, people should consider this potential risk alongside the limited evidence from this review when deciding whether to use these medicines.
What are oral decongestants?
Oral decongestants are medications taken by mouth to relieve nasal congestion (stuffy or blocked nose), often caused by colds, allergies, or sinus infections (small, empty spaces behind the cheekbones and forehead that are connected to the nose). They typically include medicines called pseudoephedrine or phenylephrine.
How do oral decongestants work?
These medicines shrink swollen blood vessels in the nasal passages. This reduces swelling and allows air to flow more freely, helping you breathe easier.
What is hypertension?
Hypertension (high blood pressure) is when resting blood pressure is consistently above 140/90 mmHg. It can lead to unwanted effects such as stroke (where the blood supply to parts of the brain is reduced or stopped) and heart attack (where the blood supply to the heart is reduced or stopped). Lowering blood pressure is the easiest way to reduce these diseases.
How is hypertension treated?
Treating hypertension involves lifestyle measures and taking blood pressure-lowering medicines. Here, we focused on the effects of daily intake of oral decongestants. While these medicines help with nasal congestion, they may also increase blood pressure.
What do we want to find out?
We wanted to find out whether long-term use of oral decongestants (for seven days or longer) increases blood pressure and has any unwanted effects. We also evaluated their effectiveness in relieving nasal congestion. This provides essential insights into their benefits and risks to guide informed use.
What did we do?
We searched for studies that compared the blood pressure effects of oral decongestants with placebo. A placebo is a substance or treatment with no active ingredients that is used in medical research to compare against the effects of real medications. We then compared and summarized the results, and rated our confidence in the evidence depending on the study design and methods.
What did we find?
We found five studies involving 882 children and adults (326 males and 591 females). The shortest study lasted one week, with the longest study lasting 24 weeks. These studies measured blood pressure and heart rate after one to seven weeks of taking oral decongestants. The size of the studies ranged from 18 to 568 people, and most were done in the USA. Pharmaceutical companies funded three studies.
We found no clear evidence that taking oral decongestants daily changes blood pressure or heart rate, or causes people to stop taking them due to unwanted effects.
What are the limitations of the evidence?
There was a limited number of studies, and they were not well designed. None of the studies were primarily designed to assess the long-term effects of oral decongestants on blood pressure. Trials designed to answer this question are needed.
How up to date is the evidence?
The evidence is up to date to July 2024.
In this systematic review, chronic daily intake of adrenergic agonist oral decongestants had little to no effect on blood pressure, heart rate, and withdrawals due to adverse effects. People making decisions about using these medicines should consider the very low certainty of evidence and the theoretical risk of increased blood pressure.
Independent trials free from biases that are designed to answer this question are required. The evidence was limited due to the small number of studies, and the blood pressure and heart rate not being measured at the optimal time after drug ingestion.
Adrenergic agonist oral decongestants are commonly taken daily over long periods of time to relieve sinus and nasal congestion. The mechanism of action of decongestants potentially increases blood pressure, and these effects may be acute or chronic.
However, no systematic reviews to date have comprehensively assessed the chronic blood pressure effects of adrenergic agonist oral decongestants as a drug class, despite their widespread non-prescription availability.
Primary objective
To assess the effects of adrenergic agonist oral decongestants on systolic and diastolic blood pressure compared to placebo.
Secondary objective
To assess the effects of adrenergic agonist oral decongestants on heart rate and withdrawals due to adverse effects.
The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials (RCT) up to July 2024: Cochrane Hypertension Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL) via Cochrane Register of Studies, Ovid MEDLINE, Ovid Embase, and ClinicalTrials.gov. There were no language, publication year, or publication status restrictions.
We included RCTs of at least seven days' duration with parallel groups (intervention and placebo) comparing adrenergic agonist oral decongestants versus placebo on blood pressure in people aged over six years.
Two review authors (JJC and MC) independently assessed the trials for inclusion, extracted the data, and assessed the risk of bias from the included trials. In cases where there were disagreements, the third review author (JMW) adjudicated. For any missing or unclear information in the studies, we contacted the study author to request the missing information or seek clarification. The primary outcomes were systolic blood pressure and diastolic blood pressure. Secondary outcomes were heart rate and withdrawal due to adverse effects. We used a fixed-effect model to combine the effect sizes from all studies. We assessed the certainty of the evidence using GRADE.
Five RCTs randomizing 882 participants met the inclusion criteria. The shortest study duration was one week, and the longest study duration was 24 weeks. These studies measured blood pressure and heart rate after one to seven weeks of taking oral decongestants. The largest study included 568 people, and the smallest study included 18 people. The mean age of participants was 20.0 years, with 326 males and 591 females. The studies were conducted in the USA and Europe; most were set in the USA. Pharmaceutical companies funded three of the five included studies.
The findings are relevant to all people using adrenergic agonist oral decongestants for seven days or longer regardless of comorbidities or pre-existing conditions. The adrenergic agonist oral decongestants included were ephedrine (one RCT), pseudoephedrine (one RCT), and phenylpropanolamine (three RCTs).
Compared to placebo, adrenergic agonist oral decongestants may have little to no effect on systolic blood pressure, but the evidence is very uncertain (mean difference [MD] 0.91 mmHg, 95% confidence interval [CI] −0.57 to 2.38; 4 RCTs, 784 participants; I2 = 54%; very low-certainty evidence). Adrenergic agonist oral decongestants may have little to no effect on diastolic blood pressure (MD 0.44 mmHg, 95% CI −0.59 to 1.48; 5 RCTs, 882 participants; I2 = 30%; low-certainty evidence). Adrenergic agonist oral decongestants may have little to no effect on heart rate, but the evidence is very uncertain (MD 1.92 beats per minute, 95% CI −0.62 to 4.47; 2 RCTs, 190 participants; I2 = 79%; very low-certainty evidence). Adrenergic agonist oral decongestants may have little to no effect on the number of withdrawals due to adverse effects (risk ratio [RR] 1.20, 95% CI 0.37 to 3.88; 4 RCTs, 806 participants; low-certainty evidence; note 1 study reported withdrawals due to adverse effects but recorded 0 events in both groups. Thus, the RR and CIs were calculated from 3 studies rather than 4).
Four studies were at overall high risk of bias, and one study was at overall low risk of bias.