You may consider taking Antihistamines if you have allergies, usually in tablet form to relieve your symptoms. Symptoms like:
- Hives (Uticaria), Allergic Rashes
- Itchy irritated skin
- Allergic Rhinitis
- Hay Fever – though they are not very effective for blockage in the nose
Certain types of antihistamine drugs block the histamine receptors in the brain. These drugs are often valuable as a treatment for travel sickness, vertigo or sickness connected with migraine. These drugs can also help to relieve tickly throats and coughs.
Some antihistamines cause sleepiness, and there are some types you can take to help you sleep, (eg over-the-counter sleep aids, such as Nytol, which contains the antihistamine diphenhydramine which causes sleepiness).
Kinds of Antihistamines
There are two primary sorts of antihistamines – non sedating and sedating.
Sedating antihistamines act on your brain and the rest of the body, and they can cause drowsiness. Examples include promethazine and chlorphenamine.
Non-sedating antihistamines do not go into the brain so easily, so they don’t make you sleepy. This also means that they do not ease nausea . Examples include cetirizine and desloratadine.
How Do Antihistamines Work?
Once an unfamiliar and potentially damaging substance enters your body, the immune system reacts by setting off various defences to guard you.
Histamine is one of the chemicals launched during an immune reaction. Its job is to help damaged tissues to heal, and in doing this, it causes swelling, itchiness and redness.
If you are sensitive to something, your immune system mistakenly mounts a response to that substance which is not truly unsafe, and releases histamine. For example, with hay fever the body confuses pollen for a damaging substance. You then get symptoms such as sneezing and red, itchy eyes.
An antihistamine works by blocking the action of histamine, and so easing the symptoms of allergic reactions.
How To Take Antihistamines
A lot of products based on antihistamines are available with no prescription from a pharmacy. Examples include chlorphenamine (eg Piriton), loratadine and cetirizine. These are generally only for short-term use. Higher doses can only be prescribed by the physician.
Antihistamines come as tablets, capsules and syrups (oral preparations), eye drops, nasal sprays and drops, lotions and injections.
If you have Hay Fever, there are a number of diverse antihistamine tablets available to treat the symptoms. It may be a good idea to begin these just before the pollen season starts, so ask your pharmacist or physician for advice.
Antihistamine creams can lead to allergic-type responses themselves, and you should not use them for more than 3 days. The hazards may possibly outweigh the benefits, so ask your pharmacist for advice.
Antihistamine auto-injectors (e.g. EpiPen) are only available by doctor prescription . They are solely used for severe allergic responses and anaphylactic shock (a potentially life-threatening allergic reaction).
Use Antihistamines With Caution
Some antihistamines may be unsuitable for kids under 12. Check the label on the medicine or ask your pharmacist for advice. Always read the patient information leaflet which comes with your medicine.
Speak to your doctor or pharmacist prior to taking antihistamines if you have a medical issue or are taking any other medicines.
You should also inform the doctor if you are pregnant or breastfeeding before taking any medications.
Side-effects of Antihistamines
The list of side-effects below does not include every possible side-effect of antihistamines. Examine the patient information leaflet that comes with the medication for more information.
Sedating antihistamines may possibly make you feel sleepy, though this may improve after you have been taking the medication for a few days. Non-sedating antihistamines seldom result in drowsiness. Drowsiness caused by antihistamines can make it unsafe to drive or run machinery.
Other, much less common side-effects, mainly from sedating antihistamines, include:
- Trouble passing urine
- Dry mouth
- Blurred eyesight
- Nausea or vomiting
- Diarrhea or constipation
- Skin or eye irritation or itching (from lotions, lotions and eye drops)
The following antihistamines side effects have also sometimes been noted:
- Palpitations and abnormal heart rhythms (arrhythmia)
- Elevated blood pressure
- Allergic reactions (such as inflammation, rash and respiration troubles)
- Depression symptoms
- Disturbed sleep
- Blood and liver disorders
- Over-excitement in children
Children and adults over 65 are far more likely to get side-effects.
Interactions With Other Medications
Check with your medical professional or pharmacist before you take any other drugs or natural remedies at the same time as antihistamines.
Please take note that alcohol can magnify the sedating effects of antihistamines.