Unwanted side effects of sedating antihistamines
You will find a full list of side-effects in the manufacturer's information leaflet supplied with your medicine but the table below contains the most common ones. Never give it to other people even if their condition appears to be the same as yours. Take them to your local pharmacy which will dispose of them for you.
The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any continue or become troublesome. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. If you have any questions about this medicine ask your pharmacist.
The most common side-effects are feeling tired or sleepy.
Make sure you follow the dosage directions on the label.
These sedating antihistamines often are used alone or in combination with other ingredients in cold and cough medications, and over-the-counter (OTC) sleep aid products.
Diphenhydramine (Benadryl) is the most common first-generation antihistamine found in OTC sleep aids, whether used alone or in combination with pain relievers, including acetaminophen (eg, Tylenol PM), ibuprofen (eg, Advil PM), and aspirin.
If affected, do not drive and do not use tools or machines until you feel better.
Chlorphenamine belongs to a group of medicines known as sedating antihistamines.
First-generation antihistamines are widely available without a prescription and commonly used to treat allergic symptoms, including rhinitis, conjunctivitis, pruritus, eczema, urticaria, and anaphylactic reactions.
Currently the only FDA-approved histamine antagonist medications block the effects of histamine at H1 or H2 receptor sites.
6 Antihistamine medications block or reduce histamine-mediated effects at one of four identified histamine receptors (see Table 1 below).
Older adults are especially sensitive to the central nervous system- and anticholinergic-related side effects of sedating antihistamines because of decreased cholinergic neurons or receptors in the brain, reduced hepatic and renal function, and increased blood-brain permeability.
These patients also often have coexisting conditions and often take multiple medications that increase the risk of drug-drug interactions and the potential for sedative adverse effects.