Can Antihistamines Used for Treating Allergies Actually CAUSE Allergies?

The world of medicine is filled with paradoxes, and one question that has been on the minds of many is whether antihistamines, commonly used to treat allergies, can actually cause them.

Antihistamines are primarily used to manage allergic conditions. Their main function is to counteract the effects of histamine, a compound released during allergic reactions that causes itching and other symptoms.

The Evolution of Antihistamines

According to the PubMed Central (PMC), the early antihistamines, often referred to as ‘first generation’ antihistamines, such as promethazine, were known to cause sedation. This sedative effect has been reduced in the newer ‘second generation’ and ‘third generation’ antihistamines like loratadine and desloratadine. The oral antihistamines available today are much more advanced and have fewer side effects compared to their predecessors.

The Role of Sedating

There’s a growing concern about the use of sedating antihistamines. Their sedative properties can interfere with rapid eye movement sleep. Studies have shown that children with allergic rhinitis treated with sedating antihistamines performed poorly in school compared to those treated with non-sedating antihistamines. There have also been reports of aviation accidents and car accidents attributed to the sedative effects of these antihistamines.

Newer Antihistamines: A Safer Alternative?

Newer Antihistamines

The newer H1 antihistamines are less sedating and are considered equally effective. While all the newer drugs seem to work well, there are limited long-term studies comparing them head-to-head. Therefore, patients often choose the drug they find most effective or the formulation that suits them best.

Allergic Reactions

The newer H1 antihistamines are the primary treatment for mild to moderate allergic reactions. However, it’s crucial to note that antihistamines have no role in the acute treatment of anaphylaxis. In such cases, intramuscular adrenaline must be administered.

Potential Side Effects: Not to be Confused with Allergies

It’s crucial to differentiate between side effects and allergic reactions when discussing antihistamines.

Common Side Effects

According to the Mayo Clinic, antihistamines can cause side effects, which vary depending on the specific drug and its formulation. Some common side effects include:

  • Drowsiness or sedation
  • Dry mouth
  • Dizziness
  • Nausea and vomiting
  • Restlessness or moodiness (in some children)
  • Difficulty urinating or not being able to urinate
  • Blurred vision
  • Confusion

It’s essential to understand that these are side effects and not allergic reactions to the medication itself.

When to Seek Medical Attention

While antihistamines are generally safe, it’s crucial to be aware of when to seek medical attention.

Signs of an Allergic Reaction

According to the American Academy of Allergy, Asthma & Immunology (AAAAI), if someone experiences symptoms like hives, swelling of the face or throat, difficulty breathing, a rapid heartbeat, or dizziness after taking an antihistamine, they might be having an allergic reaction to the medication and should seek emergency medical attention immediately.

Frequently Asked Questions

Can I take antihistamines daily?

While many antihistamines are designed for daily use, it’s essential to consult with a healthcare professional before starting any medication regimen.

Are there natural alternatives to antihistamines?

Yes, some natural remedies like quercetin, butterbur, and stinging nettle have been suggested as alternatives. However, their efficacy varies, and it’s crucial to discuss with a healthcare provider before trying them.

Can antihistamines interact with other medications?

Yes, antihistamines can interact with certain medications, leading to increased side effects or reduced effectiveness. Always inform your doctor about all the medications you’re taking.

Are antihistamines safe for pregnant or breastfeeding women?

Some antihistamines are considered safe during pregnancy and breastfeeding, while others are not. Always consult with a healthcare professional before taking any medication during pregnancy or breastfeeding.

Can children take antihistamines?

Yes, there are antihistamines formulated specifically for children. However, it’s essential to follow the recommended dosage and consult with a pediatrician.


Antihistamines play a crucial role in managing allergic reactions by counteracting the effects of histamine. While the older, sedating antihistamines have raised concerns due to their side effects, the newer generation antihistamines are considered safer and equally effective. It’s essential to consult with a healthcare professional to determine the best antihistamine for individual needs.