What happens if… you take too many antihistamines?

It’s that time of year again when allergens hold our senses hostage and we find ourselves reaching for antihistamines just to get through the day.

But what if you accidentally pop too many?

Here’s what you need to know.

Histamine is the substance your body produces when you have an allergic reaction after mistaking something harmless for a threat, according to the NHS.

This substance then causes allergy symptoms by clinging to receptors on certain cells in the body, causing hay fever, hives, conjunctivitis, reactions to insect bites or stings.

An antihistamine is the generic name for a product that helps suppress your body’s reaction to certain allergens, although they can also sometimes be used for motion sickness, nausea, vomiting, or insomnia.

The product is known to treat symptoms such as congestion, runny nose, sneezing, itching, nasal swelling, hives, rash, itchy and watery eyes.

Some can be purchased over the counter, but others are available by prescription only.

There are usually two types of antihistamines — the kind that don’t make you drowsy and the kind that make you drowsy — so it’s worth asking your pharmacist if you’re not sure which type you should take.

As the NHS explains, check with your pharmacist or doctor about how you should take your medicine, including how long you can take it for, when to take it and what other medicines you are taking.

Be sure to also ask how much to take, as this can vary based on your age and weight.

Be aware of side effects as well and make sure you can differentiate between this and a possible overdose.

According to the NHS, these are the most common side effects:

• Drowsiness, impaired coordination, reaction speed and judgment
• Dry mouth
• Blurred vision
• Difficulty urinating

Non-drowsy antihistamines

• Heachache
• Dry mouth
• I do not feel well
• Drowsiness

These symptoms may be similar to the normal side effects of taking the drug, but usually subside fairly quickly. However, it is still worth talking to a doctor if you experience any side effects as your dose may need to be adjusted.

When it comes to distinguishing between an overdose and regular side effects, it all boils down to the severity of the symptoms, according to the U.S. medical outlet Healthline.

Overdose with sleepy antihistamines:

• Increased drowsiness
• Blurred vision
• Nausea
• Vomit
• Increased heart rate
• Confusion
• Loss of balance

In extreme cases, even drowsy antihistamines can trigger seizures and coma.

Symptoms of overdose with non-drowsy antihistamines:

Non-drowsy antihistamines are typically less toxic and trigger less severe symptoms, but they can still trigger:

• Dizziness
• Heachache
• Drowsiness
• Shaking

Symptoms of an overdose usually show up within six hours of taking too much of the drug and can start out mild and get worse.

If you notice that you are struggling with a racing heart, tightness in your chest, or seizures, you need to go to the hospital.

It is possible to die from it, from respiratory distress, cardiac arrest or seizures, depending on each person’s tolerance.

According to Healthline, the drug becomes toxic when a person ingests three to five times the recommended dose.

Professionals will give a patient activated charcoal in the hospital to reverse the effects of the poisoning.

This will stop the absorption of toxins and chemicals from the stomach into the body as the toxins stick to the charcoal and then exit in your poop.

You may also have heart and respiratory monitoring.

Healthline adds, “The prognosis depends on the amount of antihistamine ingested and the extent of an overdose, but a full recovery is possible with immediate medical attention.”

Be sure to talk to healthcare professionals before taking the drug, and don’t take two different types at the same time or exceed the recommended dose.

Do not double the doses and be sure to space the doses at the correct length.

Also, be careful about what other medications you are taking.

You also shouldn’t give an antihistamine to a child under 2, according to Healthline — and, of course, always read the label.