Powered by Smartsupp

CBD and allergies: inetraction with antihistamines

Allergies to animals? Pollen? Dust? No matter what's causing your sneezing, an allergic reaction to environmental stimuli can affect your life far more than healthy people realize. If you are reliant on regular or even daily use of allergy medication - antihistamines - to keep allergy symptoms at bay, you may be wondering if CBD oil can be safely added to your life. In this text, we bring you a medically revised explanation of how CBD oil can potentially interact with some of the most commonly used antihistamines. This information will help you make an informed decision about whether or not CBD is right for you.

The information contained on this page is intended as an educational tool and should not replace a consultation with a physician.

How CBD oil reacts to antihistamines
Side effects of CBD oil and antihistamine interaction
Benefits of taking CBD for allergy suppression
Best CBD oils for allergy sufferers
CBD oil dosage

How CBD oil reacts to antihistamines

Although most research shows that taking CBD oil is safe and has almost no side effects, it can pose a risk when you are taking certain medications. Specifically, these are those that act on the cytochrome P-450 enzyme system. The P-450 system is responsible for both the detoxification of foreign chemicals and the metabolism of many common drugs. CBD oil, along with grapefruit and some other natural substances such as St. John's Wort, have been shown to inhibit (inhibit) the P-450 system. When this system is inhibited, drugs take longer to metabolize and so levels of substances from the drugs can build up in the blood.

Because antihistamines (allergy medications) use the P-450 system, taking them along with CBD oil can slow your body's ability to break them down. This will cause more antihistamines to be present in your body at any given time, making it more likely that you will experience side effects. Therefore, if you are taking antihistamines on a daily basis, you should be careful and consult your doctor before taking CBD oil. The benefits of cannabidiol (CBD) may not outweigh the side effects of combining it with your antihistamines.

Side effects of CBD oil and antihistamine interaction

Most commonly used antihistamines contain one of the following key ingredients: loratadine (Claritine), cetirizine (Zodac, Xyzal, Zyrtec, Analergin), fexofenadine, or diphenhydramine. Each of these works differently in the body to achieve similar results, and each carries with it a number of potential side effects. Combining the use of drugs containing these active ingredients with CBD oil increases the chances of these side effects manifesting.

The following table breaks down common antihistamines and their side effects and how CBD oil could affect the likelihood of their occurrence.

  • Generic name of the antihistamine
  • Common names
  • Possible side effects
  • Possible side effects when taking CBD oil at the same time
  • Loratadine
  • Loratadine, Claritine
  • Headache, stomach pain, insomnia, dry mouth, nervousness
  • CBD oil increases the risk and/or severity of side effects
  • Cetirizine
  • Zyrtec
  • Drowsiness, stomach pain, vomiting, diarrhea
  • CBD oil increases risk and/or severity of side effects
  • Fexofenadine
  • Allegra
  • Headache, vomiting, body pain, dry mouth
  • CBD oil increases the risk and/or severity of side effects
  • Diphenhydramine
  • Benadryl
  • Drowsiness, vomiting, loss of appetite, constipation
  • CBD oil increases risk and/or severity of side effects

It is important to consider potential side effects before taking CBD-containing products at the same time as any antihistamines. If a potential side effect of the medications is drowsiness, which could be exacerbated after concomitant use of CBD, it would be a good idea to avoid driving, operating heavy machinery, or performing any tasks that require alertness or concentration while taking both antihistamines and CBD. Consider the side effects and plan your activities accordingly.

Elderly people or individuals taking multiple medications, such as antihistamines, that have central nervous system or respiratory depressant effects should be monitored closely as these effects may be amplified after taking CBD oil. This is also true if you are taking medication for high blood pressure, as cannabidiol is known to counteract hypertension as well.

If you have experienced side effects from taking antihistamines in the past, it is wise to avoid CBD oil while taking them. It is quite possible that it will not have a negative effect on you, but until you are sure, use CBD oil with caution.


Benefits of taking CBD for allergy suppression

There are a number of potential health benefits of taking CBD, some of which are particularly promising for allergy sufferers.

For starters, CBD oil can reduce the incidence of seasonal allergies. Cannabidiol helps regulate the function and production of white blood cells, which play a key role in the inflammatory response to potential allergens. CBD is anti-inflammatory and antimicrobial, making it ideal for irritated sinuses and respiratory tract. CBD has even been the subject of research for its potential to reduce allergy-induced inflammation in asthma sufferers.

Keep in mind that there are slight risks associated with taking CBD oil along with antihistamines, and you'll need to decide if the potential benefits outweigh these potential risks. If you would like to explore this treatment option further, consult your doctor first. 

Best CBD oils for allergy sufferers

If your doctor confirms that it's okay to take CBD along with allergy medication, you should find the best quality CBD oil on the market.

Start by finding a brand that produces organically grown products to ensure that the CBD oil will be pesticide-free. You should also look for CBD companies that use third-party lab tests to verify the potency and purity of their products. Independent party lab reports provide a detailed breakdown of all the compounds - both good and bad - found in each batch of a company's product. If you come across a manufacturer that doesn't provide certificates of analysis, you're better off looking elsewhere.

Once the choice of CBD product brand is behind you, you need to decide how you want to use cannabidiol.

CBD-containing capsules and ingestibles are an easy way to incorporate CBD into your daily regimen, such as in combination with your morning coffee. The only downside to taking CBD in the form of edibles is that you will have to wait longer for the effects to take effect, as CBD has to pass through the digestive system first. The effects of CBD capsules or edibles usually last 4-6 hours, making them an ideal method of administration if you suffer from chronic allergies.

A vaporizer pen is a great option for taking CBD oil if you need it during the day, as it is the fastest acting form of administration. The effects of CBD drops and tinctures don't come on as quickly as with a vaporizer pen, but you will feel the effects for a relatively longer period of time.

If you usually experience sudden onset of allergy symptoms, vaporizing CBD or taking CBD oil may be the best option. In both of these cases, the CBD does not have to pass through the digestive system before being absorbed into the bloodstream, so the onset of effect is very quick.  Finally, if you are itching with an allergic rash or hives, you can try a CBD cream. This cream can act directly on the affected area and provide targeted relief throughout the day.

CBD oil dosage

When it comes to dosing, follow the recommendations listed with your chosen CBD product, or you can take inspiration from this CBD dosing guide for beginners. While the ideal CBD oil dosage depends on a number of individual factors, such as your weight and metabolic rate, you can use a standard dosage to get started:

Standard CBD dosage: 25 mg of CBD taken twice a day.

If this amount doesn't give you the results you want, we recommend increasing the dose size by 25 mg every 3-4 weeks until you feel relief. If in doubt, always consult a doctor before combining treatment options.



Each brand has a responsibility to its customers. Hemnia is dedicated to natural remedies and a harmonious lifestyle. We like to write about these things and share our good experiences. In addition to verified quality and correct, understandable descriptions for our products, we have a duty to make you aware of what we can and cannot be held responsible for. The goal is your safety and we fully respect that.

Photo: Shutterstock 

Short and simple:
 1. Hemnia does not want to, nor can it, replace the professional care of your doctor.

2. Hemnia products are not drugs (aka medicines), so please don't treat them as such.

3. Hemnia offers cannabis products, but do not look for any narcotic or psychotropic substances. We do not offer or recommend them.

Read the full text of the disclaimer here.