Antihistamines

Antihistamines are medications that counteract the effects of histamine, a chemical released by the body's immune system during an allergic reaction. They're commonly used to relieve symptoms of allergies, such as:

1. Itching
2. Sneezing
3. Runny nose
4. Congestion
5. Hives

Antihistamines work by blocking histamine receptors, reducing the allergic response. They come in various forms, including:

1. Over-the-counter (OTC) medications
2. Prescription medications
3. Topical creams or ointments

Some common side effects of antihistamines include:

1. Drowsiness
2. Dry mouth
3. Dizziness
4. Stomach upset

There are two main types of antihistamines: 1. First-generation antihistamines (e.g., diphenhydramine): More likely to cause drowsiness and other side effects. 2. Second-generation antihistamines (e.g., loratadine, cetirizine): Less likely to cause drowsiness and other side effects. Antihistamines are often used to treat conditions like:

1. Allergic rhinitis (hay fever)
2. Urticaria (hives)
3. Itchy skin conditions (e.g., eczema)
4. Insect bites or stings

Antihistamines can cause several ocular side effects, including: Common Ocular Side Effects

1. Dry eyes: Reduced tear production can lead to dry, irritated eyes.

2. Blurred vision: Antihistamines can affect the eyes' ability to focus.

3. Increased intraocular pressure: Some antihistamines may worsen glaucoma or increase the risk of developing it.

4. Pupillary dilation: Some antihistamines can cause pupils to dilate, potentially increasing sensitivity to light.

5. Conjunctival injection: Redness and inflammation of the conjunctiva.

Less Common Ocular Side Effects 1. Double vision: Some antihistamines can affect eye muscle coordination. 2. Decreased accommodation: Difficulty focusing on near objects.

Precautions 1. Contact lens wearers: Dry eyes can be particularly problematic for contact lens wearers. 2. Glaucoma patients: Certain antihistamines may worsen glaucoma symptoms. Management 1. Artificial tears: Using lubricating eye drops can help alleviate dry eyes. 2. Consult a HCP: If you experience persistent or severe ocular side effects, consult an Eye Doctor for guidance.