Dimenhydrinate

Benjamin Clanner-Engelshofen is a freelance writer in the medical department. He studied biochemistry and pharmacy in Munich and Cambridge / Boston (USA) and noticed early on that he particularly enjoyed the interface between medicine and science. That is why he went on to study human medicine.

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The active ingredient dimenhydrinate is one of the most commonly used drugs against nausea and vomiting when traveling (seasickness or motion sickness). The most common side effects are fatigue and drowsiness. Here you can read everything you need to know about dimenhydrinate: use, effect, interactions and side effects.

This is how dimenhydrinate works

Dimenhydrinate is an antiemetic, i.e. a remedy for nausea and vomiting. From a chemical point of view, it is a combination of two separate particles: diphenhydramine and chlorotheophylline. The latter is added as a mild stimulant (similar to caffeine) to alleviate the tiredness that often occurs after the administration of diphenhydramine. Diphenhydramine actually works against nausea when traveling.

The brain continuously collects information from the environment with the help of the various sensory organs. Historically very old functions of the brain often converge in the brain stem, including the evaluation of the body's position in space and its movement. When you sit in a vehicle, the brain sees the movement, but does not feel any acceleration through the inner ear at a constant speed, and the muscles also do not report any movement. This contradicting information causes the brainstem to activate an alarm program which manifests itself in malaise, nausea and dizziness.

The active ingredient dimenhydrinate reaches a region on the back of the brainstem called the "area postrema" via the bloodstream. There are many docking points for messenger substances (including acetylcholine and histamine) and toxins from the blood that cause nausea and vomiting. Dimenhydrinate blocks these docking sites and thus mediates its effect, which alleviates nausea and vomiting.

After ingestion, dimenhydrinate enters the bloodstream via the intestines. After three to six hours of action, it is broken down in the liver and excreted in the urine via the kidneys.

When is dimenhydrinate used?

The active ingredient dimenhydrinate is approved for the prevention and treatment of nausea and vomiting of various causes - but above all for motion sickness. It is not suitable for treating nausea during chemotherapy.

It should only be taken without a doctor's prescription for a short time before and during the trip.

This is how dimenhydrinate is used

In self-medication, dimenhydrinate is taken in the form of tablets or chewing gum. A single dose usually contains 50 milligrams of dimenhydrinate. For prevention, a tablet or chewing gum is taken half an hour before the start of the journey and then up to three times a day. If nausea or vomiting occurs during the trip, one or two tablets are taken every four hours, but no more than six tablets (equivalent to 300 milligrams of dimenhydrinate) per day. Ingesting larger amounts of the active ingredient can cause hallucinations. Therefore it is also used improperly as the "dimenhydrinate drug", but only from doses above 400 milligrams.

What are the side effects of dimenhydrinate?

The intake of dimenhydrinate also leads to tiredness and sleepiness in many travel sick, but this effect can also be desired from time to time.

One in one hundred to one thousand patients also experience side effects such as restlessness, excitement, sad or exuberant mood, movement disorders, dizziness, cramps, constipation, dry mouth, problems urinating, visual disturbances and allergic reactions with rashes and itchy skin. In the event of allergic symptoms, the intake must not be continued.

What should be considered when taking dimenhydrinate?

The combined intake with other active ingredients, even if this takes place at different times of the day, can lead to interactions.

If dimenhydrinate is combined with centrally acting drugs (psychotropic drugs) or alcohol, the depressant or excitatory effect can be increased.

Taking certain active ingredients for depression (amitriptyline, imipramine, tranylcypromine, moclobemide) can lead to increased side effects such as dry mouth and constipation.

Medicines that lower blood pressure may have a stronger effect if dimenhydrinate is also taken. The intake should therefore be clarified with the doctor beforehand.

Dimenhydrinate weakens the effect of anticoagulants such as heparin and the anti-inflammatory effect of glucocorticoids ("cortisone").

The active ingredient dimenhydrinate can be used in a reduced dose in children from six years of age. Older patients can also be treated with dimenhydrinate - unless they suffer from increased intraocular pressure (glaucoma, glaucoma), epilepsy or an enlarged prostate. Pregnant and breastfeeding women are also not allowed to take dimenhydrinate.

How to get drugs with dimenhydrinate

Preparations containing dimenhydrinate for ingestion (such as tablets, chewing gum, and slow-release capsules) and suppositories are pharmacy-only and can be bought without a doctor's prescription.

Injection preparations require a prescription. The same applies to combination products with active ingredients that require a prescription.

Since when has dimenhydrinate been known?

In the 1940s, antiallergic agents (antihistamines) came on the market, but they all had severe fatigue as a side effect. With the combination of diphenhydramine and chlorotheophylline, the pharmaceutical company G. D. Searle and Company in the USA has for the first time come up with a formulation that leads to less fatigue. During the first tests on patients with hives, it was discovered by chance that dimenhydrinate helps against motion sickness. At the end of the 1940s, the new drug with the active ingredient dimenhydrinate came onto the market in the USA and Germany.

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