Around 16 million Britons suffer from hay fever, and many will turn to over-the-counter antihistamine medications for some much-needed relief during the season.
However, Dr Rupa Parmar, GP and Medical Director of Midland Health, is warning that commonly used antihistamines can react poorly with other medications, causing uncomfortable but avoidable side effects.
Dr Rupa Parmar said: “My advice is always to double-check which medications interact with one another. This goes for any medicines, not just antihistamines. Ensure you read the information booklet, or even easier, talk to a pharmacist who can inform you on which medications you can take together.”
Drowsy Antihistamines
Known as first-generation antihistamines, some allergy medications can make you drowsy and cause sleepiness, reduced alertness, blurred vision, or difficulty urinating.
Generally, they are extremely effective for fast relief and reducing insomnia. But they can react poorly and cause extreme side effects when used alongside other sedating medications like sleeping pills, certain antidepressants, muscle relaxants, and cough and cold medicines that already contain antihistamines.
It’s also so important not to drink alcohol when taking first-generation antihistamines, as it greatly increases the sedative effects. You should also avoid driving with any medication that causes drowsiness.
Non-Drowsy Antihistamines
Most antihistamines are second-generation, which are less likely to cause sleepiness and are preferable for daily use. Common side effects of non-drowsy antihistamines are headaches, nausea, and a dry mouth.
Non-drowsy antihistamines have fewer interactions than drowsy ones. But it’s worth noting that some antacids for indigestion or stomach ulcers can interfere with how well the medication is absorbed in the digestive tract, making it less effective.
Decongestants
Decongestant antihistamines that target both allergy and cold symptoms can increase heart rate and blood pressure, so they shouldn’t be used with medications that do the same.
Decongestants can also decrease the effectiveness of blood pressure medications, including beta blockers, and stimulant medications, usually used for ADHD. Interactions can also occur with caffeine, other stimulants, and cough and cold medications.
Anyone with high blood pressure, heart disease, thyroid issues, diabetes, or an enlarged prostate should consult a doctor before using decongestants, as they can make the condition worse.
