Antihistamine Side Effects

Antihistamines are drugs that are most commonly prescribed by doctors to treat hay fever and some types of allergies. They work by blocking the receptor sites of histamines which are chemicals released by the body as a result of its response to foreign entities entering the body. Although the drugs are popular, there are certain side effects that a user must be aware of. One's physician will take care that he does not prescribe these drugs if the patient is suffering from certain conditions in which consumption of the drugs may cause complications. However, it is best to do some research and self educate oneself about the various side effects of the drug.

How do Antihistamines Work?

Our system has its mechanism in place to defend our body from the effects of being invaded by foreign substances, like pollens. These foreign substances are generally referred to as allergens. In response to the allergens, our body's defense system releases a number of chemicals, one of them being the histamines.

Histamines are stored in the mast cells present in every tissue of the body. When they attach to specific receptor sites, they trigger a number of reactions, one of which is itching. Antihistamines bind to the H-1 histamine receptors preventing the histamines from binding to the site. Stopping the itching sensation is important as due to excess itching, the skin breaks and is open to more infections. However, it is important to understand that histamines are just one of the factors that cause itching. Other than itching, antihistamines also alleviate red and irritated eyes, sneezing and runny nose.

The Side Effects

Despite their efficiency, there are certain side effects of antihistamines. While some individuals may experience a couple of the effects, other may not feel any. Antihistamine side effects in children and elderly people are more frequent than in individuals of other age groups. Some common side effects are:

• Headache
• Drowsiness
• Dry mouth
• Dizziness
• Blurred vision
• Confusion
• Constipation

Most of these side effects are mild and subside once the body adjusts to the drug. Other than these, blood pressure too is affected by the usage of these drugs. This manifests as low blood pressure. However, some even experience serious side effects like irregular heartbeat, difficulty in breathing and urinating, ringing sound in the ear, sweating, vomiting, fevers and chills, uncontrolled movements and increased sensitivity to light and fainting. In such cases, a physician must be contacted immediately.

Precautions

Other than the side effects discussed above, antihistamines should not be taken under certain conditions which include some health problems and medicines that an individual may be on. It should be avoided by those who suffer from glaucoma, thyroid and lung problems, high blood pressure, enlarged prostate seizures and liver and heart diseases. Besides those mentioned above, one must inform his physician of any other health conditions before he starts taking these medicines. Also those individuals who are on sedatives, sleeping pills, other cold and allergy medicines, tranquilizers, antidepressants, muscle relaxers or are consuming seizure medications must not take antihistamines as they may interact with these drugs and cause adverse effects. Those who are going for allergy testing must also discontinue the use of antihistamines as these drugs may interfere with the results of the tests.

Antihistamines have a sedative effect, therefore one should not take these medicines before doing activities like driving that require alertness of mind. It is best to take these medicines before going off to bed. Pregnant women and those who are breastfeeding are also advised against using these medicines as they can have serious side effects in children especially those below the age of twelve. As far as medicines are concerned, one should be very careful with the dosages. In case you have missed a particular dose, don't fret over it. Just skip it and start afresh with the next dose.

In case of the severe side effects, one definitely needs to call his physician. However, if one experiences the milder side effects of antihistamine that he feels is interfering with his day-to-day activities or the side effects persists over a couple of days, then he shouldn't make delays in getting medical help.