Antihistamines
What types of OTC antihistamines are available?
What symptoms can OTC antihistamines treat?
Will an OTC antihistamine work as well as a prescription one?
What are some common side effects of OTC antihistamines?
Could OTC antihistamines cause problems with any other medicines I take?
Should I avoid any foods, drinks or activities while taking antihistamines?
Who shouldn’t take antihistamines?
What should I look for on the drug label?
See Also:
Antihistamines: Understanding Your OTC Options
This information was developed as part of an educational program made possible by an unrestricted educational grant from McNeil Consumer & Specialty Pharmaceuticals.
What types of OTC antihistamines are available?
Over-the-counter (OTC) drugs are medicines you can buy without a doctor’s prescription. Two types of OTC antihistamines are available: first generation and the newer second generation antihistamines.
First-Generation OTC Antihistamines
- Brompheniramine (brand names: Dimetapp Cold & Allergy Elixir, Robitussin Allergy & Cough Liquid)
- Chlorpheniramine (one brand name: Singlet)
- Dimenhydrinate (one brand name: Dramamine Original)
- Diphenhydramine (some brand names: Benadryl Allergy, Nytol, Sominex)
- Doxylamine (two brand names: Vicks NyQuil, Alka-Seltzer Plus Night-Time Cold Medicine)
Second-Generation OTC Antihistamines
- Loratadine (some brand names: Alavert, Claritin)
Note: Both types of antihistamines often are mixed with other drugs, such as pain relievers or decongestants. Many of the brand names above are for these combination medicines, which are meant to treat many symptoms at once.
How do antihistamines work?
Histamines are substances that try to attach to the cells in your body and irritate them. Histamines can cause itching, sneezing, a runny nose and watery eyes. Antihistamines prevent histamines from attaching to your cells and causing symptoms.
Antihistamines also work in the part of the brain that controls nausea and vomiting. This is why they can help prevent motion sickness.
Antihistamines also work in the part of the brain that controls nausea and vomiting. This is why they can help prevent motion sickness.
What symptoms can OTC antihistamines treat?
Antihistamines can help prevent and treat the symptoms of allergies, colds and the flu (influenza). These symptoms include sneezing, itchy and watery eyes, and a runny nose. Antihistamines can also relieve itchiness caused by insect bites and stings, poison ivy and poison oak.
Some antihistamines are used to prevent motion sickness. Because one of the most common side effects of antihistamines is feeling sleepy, they are sometimes used to help people who have insomnia.
Some antihistamines are used to prevent motion sickness. Because one of the most common side effects of antihistamines is feeling sleepy, they are sometimes used to help people who have insomnia.
Will an OTC antihistamine work as well as a prescription one?
In general, OTC antihistamines work as well as prescription medicines.
What are some common side effects of OTC antihistamines?
Side effects from antihistamines aren’t common for healthy adults. However, side effects can be a concern for older adults or people who have health problems.
First-generation antihistamines can make you feel very sleepy. This can affect your ability to drive or operate machines. It can also make it hard for you to think clearly. Antihistamines can cause your mouth and eyes to feel dry. Second-generation antihistamines are not as likely to cause these side effects.
First-generation antihistamines can make you feel very sleepy. This can affect your ability to drive or operate machines. It can also make it hard for you to think clearly. Antihistamines can cause your mouth and eyes to feel dry. Second-generation antihistamines are not as likely to cause these side effects.
Could OTC antihistamines cause problems with any other medicines I take?
Yes. Antihistamines can interact with other drugs you take. If certain drugs are taken at the same time, they can interact with each other and change the way your body processes them. This is called a drug interaction. When this happens, the risk of side effects increases.
If you take any of the following drugs, talk to your doctor before taking a first-generation antihistamine:
If you take any of the following drugs, talk to your doctor before taking a first-generation antihistamine:
- Sleeping pills or sedatives
- Muscle relaxants
- High blood pressure medicine
Antihistamines are often combined with decongestants and/or pain relievers. If you take one of these combination medicines, it’s important to understand each of the active ingredients and the interactions they may have with other drugs you’re taking.
Be sure not to “double up” on antihistamine. Many OTC cold and allergy products contain antihistamines, as do some prescription drugs. If you take more than one of these products, you can take much more antihistamine than you intend.
See the Know What’s in the Medicines You Take chart (PDF file: 6 pages / 75 KB. More about PDFs.) to help sort out which drugs have the same ingredient so you can avoid taking too much.
Be sure not to “double up” on antihistamine. Many OTC cold and allergy products contain antihistamines, as do some prescription drugs. If you take more than one of these products, you can take much more antihistamine than you intend.
See the Know What’s in the Medicines You Take chart (PDF file: 6 pages / 75 KB. More about PDFs.) to help sort out which drugs have the same ingredient so you can avoid taking too much.
Should I avoid any foods, drinks or activities while taking antihistamines?
Alcohol can increase the drowsiness caused by antihistamines. Also, be very careful if you drive a car or run machines while taking an antihistamine. Antihistamines may slow your reactions without you even being aware of it.
Who shouldn’t take antihistamines?
Talk to your doctor before using a first-generation antihistamine if you have any of the following health problems:
- Glaucoma
- Trouble urinating (from an enlarged prostate gland)
- Breathing problems, such as asthma, emphysema or chronic bronchitis
- Thyroid disease
- Heart disease
- High blood pressure
Before taking a second-generation antihistamine, tell your doctor if you’ve ever had kidney or liver disease.
What should I look for on the drug label?
When choosing an OTC antihistamine, check the drug label for possible side effects or interactions with other drugs you’re taking. This information will appear in the “Warnings” section of the label.
Be sure to check that you’re not taking two medicines that contain the same ingredient. You will find this information in the “Active Ingredient” section.
Always read and follow the directions on the label. Be sure you understand what the label says before taking the medicine. If you have any questions, ask your family doctor or pharmacist.
Be sure to check that you’re not taking two medicines that contain the same ingredient. You will find this information in the “Active Ingredient” section.
Always read and follow the directions on the label. Be sure you understand what the label says before taking the medicine. If you have any questions, ask your family doctor or pharmacist.
More Information
Source
Written by familydoctor.org editorial staff.
American Academy of Family Physicians
Reviewed/Updated: 10/06
Created: 09/05
Copyright © 2005-2008 American Academy of Family Physicians
|This article provides a general overview on this topic and may not apply to everyone. To find out if this article applies to you and to get more information on this subject, talk to your family doctor.
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|This article provides a general overview on this topic and may not apply to everyone. To find out if this article applies to you and to get more information on this subject, talk to your family doctor.
For private, noncommercial use only.
Home | Privacy Policy | Contact Us | About This Site | What's New |