What is this? Antihistamines are also one of the groups of drugs known for causing brain fog and memory loss. Disturbingly, even over-the-counter antihistamines like Benadryl can greatly increase the risk of dementia. The sedative effects of these drugs can leave you feeling drowsy.
Over-the-counter medications such as Benadryl and other antihistamine allergy medications also can lead to temporary brain fog and forgetfulness.
Such medications interfere with the action of an essential brain chemical called acetylcholine. There is growing concern that they could increase the risk for cognitive decline and dementia in older people.
First-generation (older) allergy medications may cause memory loss. However, newer antihistamines, cetirizine (Zyrtec) and loratadine (Claritin) are less likely to cause problems with memory and cognition.
Unrelated to the immune system, histamine is also produced in the brain, where it plays an important part in feeling awake. Antihistamines used to treat respiratory symptoms can get into the brain and interrupt this work, making you feel drowsy.
Since the effects of Zyrtec last 24 hours, drowsiness can hit at any time. Avoid alcohol and be careful about driving if the med hits you with the sleepies, per the Zyrtec site.
Effects persist for at least 24 hours following a single dose of Zyrtec. No tolerance has been found to Zyrtec's antihistaminic effect. Once discontinued, the skin recovers its normal reactivity to histamine within three days.
The most commonly reported side effects include somnolence, dizziness, and headache. Use these dosage charts for infants and children under 12 years old: Zyrtec Dosage Charts (Infants & Children)
Many people using this medication do not have serious side effects. Tell your doctor right away if you have any serious side effects, including: difficulty urinating, fast/irregular/pounding heartbeat, shaking (tremor), mental/mood changes (such as anxiety, confusion, nervousness, restlessness), weakness.
Many allergy sufferers describe an experience known as “brain fog” — a hazy, tired feeling that makes it difficult to concentrate.
Older antihistamines are sedating because the medication penetrates the blood-brain barrier, which means that the medication not only works in treating allergy but also affects the brain. The result is a feeling of lethargy.
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Over time, your body becomes desensitized to the allergens, and your immune response lessens. Eventually, your body may stop reacting to the allergens altogether, giving you long-term relief from your allergy symptoms, including brain fog.
Cetirizine is classed as a non-drowsy antihistamine, but some people still find it makes them feel quite sleepy. Common side effects include headaches, dry mouth, feeling sick, dizziness and diarrhoea.
Rarely, they can cause acute self-limited liver injury. One study has reported a more serious long-term effect, a 3.5-fold increase in the risk of gliomas, a common type of brain tumor in patients with long-term antihistamine use for allergic conditions.
Mechanism of Injury. The cause of acute liver injury from cetirizine is not known. It is metabolized by the liver and a toxic metabolite may account for idiosyncratic injury.
You should not use Zyrtec-D if you have narrow-angle glaucoma, severe high blood pressure (hypertension), severe coronary artery disease, if you are unable to urinate, or if you are allergic to hydroxyzine (Atarax, Vistaril). Do not use this medicine if you have taken an MAO inhibitor in the past 14 days.
Do not use with any other antihistamines applied to the skin (such as diphenhydramine cream, ointment, spray) because increased side effects may occur. Cetirizine is very similar to hydroxyzine and levocetirizine. Do not use these medications while using cetirizine.
Is it okay to take ZYRTEC® over a long period of time? The ZYRTEC® package label doesn't state a limit on how long you can take ZYRTEC®. Talk to your doctor if you have any questions, especially if you're taking other medicines or being treated for any other conditions.
Claritin and Zyrtec are effective and safe for most people with minor allergies.
Dr Grant confirms that many people can suffer withdrawal symptoms if they stop taking antihistamines suddenly. Dr Grant recommends the patient resume taking the antihistamines and then slowly reduce the dose to wean off slowly.
Allergic Sinusitis Can Cause Brain Fog
Individuals who feel dazed and unable to think well often describe their problem as brain fog. While brain fog may occur in association with many health problems, most notably fibromyalgia, it can also occur as a side effect of a condition called allergic sinusitis.
Poor mental performance and “brain fog”
Many people with allergy problems also deal with “brain fog.” This usually means a combination of fatigue, dizziness, imbalance, and reduced concentration. Scientists are trying to understand the connection between allergies and brain fog.