BBC doctor delivers verdict on antihistamines causing weight gain

Millions of people in the UK suffer from hay fever and other allergies that see them taking antihistamines to control their symptoms. However, despite the common nature of this medication, Dr Punam Krishan warned that many people may be taking it incorrectly and warned people not to stop taking their medication s simply because of some headlines . Speaking on BBC ’s Morning Live, the NHS GP warned that one particular claim that antihistamines could cause weight gain may be particularly dangerous, even if there is some science behind it. She said: “Histamine can affect things like your hunger and energy levels so of course antihistamines can affect that. “This isn’t a common phenomenon, it’s not a side effect that’s listed. There’s not a huge amount of evidence that suggests antihistamines, especially newer ones that are non-drowsy, cause any significant weight gain. “I don’t want anyone panicking. I don’t want anyone stopping their antihistamines. If you notice you are hungrier just be mindful of that and if something’s affecting you like fatigue speak to your GP and we can always change which one you’re on.” Histamine is a chemical the body releases when it thinks it has come into contact with something harmful. In the cases of allergies and hay fever , this reaction is a bit more extreme than it should be. This causes symptoms like sneezing, coughing, blocked or runny nose, itchy or red eyes, loss of smell, headaches or fatigue. Antihistamines work by blocking histamine in the body, preventing the reaction from starting in the first place. Dr Punam revealed she’s been prescribing antihistamines as early as February this year, but noted some people could be taking them incorrectly. She revealed that timing and consistency are a lot more important than some people think and explained why the liquid you take the medication with could prevent it from working. She said: “With hay fever, it’s not just about what antihistamine you take, it’s about when you take it and when you start it. If you know seasonal allergies is a thing for you, try and get ahead of the curve and start taking them early.” She addressed some other misconceptions about the medication, too, stating that there’s no such thing as building a tolerance to antihistamines: “Nor do you develop a tolerance to it. If something is working for you, absolutely take it every year, it will do the trick.” Other people may take antihistamines until their symptoms ease and then stop medicating, which can make their situation even worse by developing “rebound symptoms”. The NHS GP assured there’s no single antihistamine that works better than the rest and encouraged people to try different medications until they find one that works for them and then stick to that. The NHS website has a lookup tool which can make this search a bit easier and help people learn more about the antihistamines they’re already taking. Dr Punam added: "I think this is lesser known. There's a very common antihistamine called fexofenadine, which people take now. “What people don't know is that there is a transporter in the gut that fexofenadine is absorbed via. Now, there are certain fruit juices like orange juice, grapefruit juice and apple juice that can actually block that transporter, so it means that the absorption of fexofenadine is affected and significantly reduced by about 70%." The NHS website has a similar warning: “Do not drink grapefruit juice, apple juice or orange juice while you're taking fexofenadine as the medicine may not work as well. Dr Punam recommended that people on this antihistamine take their medication with water and avoid any fruit juices for a few hours before and after taking the pill. Antihistamines can also interact with other drinks, such as alcohol, which can make hay fever worse by increasing histamine in the body or worsen the drowsy side effects of some antihistamines. Dr Punam added: "Alcohol is a sedative. So if you're combining that with antihistamines, it can potentially make you feel more drowsy. It affects your alertness, your reaction times, etc. So just be wary of that."