How quickly does caffeine work


The duration of action of caffeine

Caffeine starts to work as soon as it has been absorbed from the gastrointestinal tract and entered the bloodstream. Usually this is the case after 15 to 30 minutes. If milk is added to coffee or a large meal (for example a piece of cream cake) is consumed while drinking coffee, it takes a little longer for the caffeine to achieve its stimulating effect. Within three to five hours, half of the caffeine is usually broken down again and leaves the body in the urine.

How strongly a person reacts to caffeine also depends on how often they consume the stimulating substance. For example, if you drink eight cups of coffee every day, you gradually get used to it and the effects of the caffeine wear off a little.

Can Caffeine Relieve Headaches and Depression?

Caffeine helps against this in several ways a headache and migraine: On the one hand, it ensures that the blood vessels constrict again and the blood flows better. On the other hand, it blocks the so-called prostaglandin synthesis (in short: the connection of tissue hormones that can trigger inflammatory processes in the body and pain) - and thereby inhibit pain. Some pain reliever preparations therefore also contain caffeine. A German study with 1743 patients showed that tension headaches and migraines can be treated particularly effectively with a combination preparation consisting of 250 mg ASA, 200 mg paracetamol and 50 mg caffeine.

Whether caffeine too depressions helps has not yet been clearly proven. Researchers at Havard Medical School (USA) evaluated the health and nutritional data of 50,000 US citizens and found that women who had little or no coffee were more likely to suffer from depression than coffee lovers. In particular, people who consumed at least four cups of coffee a day had a 20 percent lower risk of suffering from depression. It could not be clarified whether the caffeine is actually the reason for this. The fact is that people who are depressed often suffer from insomnia and therefore reduce the amount of coffee.

Scientists at the Pontificia University in Porto Alegre (Brazil) have come to the conclusion that caffeine has rather different effects on the psyche: Consumed in small amounts, it can protect against mood swings, but a high amount of caffeine can promote these. The following applies: anyone who drinks up to four cups of coffee a day promotes mental stability.

Does caffeine promote weight loss and hair?

Regular coffee consumption could boost fat burning and thus promote weight loss, claim scientists from the University of Nottingham. However, this only applies to black coffee. If milk or sugar is included, the opposite effect can occur.

Whether caffeine can stimulate hair to grow on a bald head and provide more head of hair has not yet been scientifically proven.

What amount of caffeine per day is okay?

The right amount of caffeine for adults: Taking a coffee to go on the way to work, going to the coffee machine more often in the office, that is part of everyday life for many Germans. But which daily dose of caffeine is healthy and which is harmful? Adults can safely consume up to 200 mg of caffeine at a time (that's the equivalent of two to three cups of coffee or 2.5 cans of energy drink), explains the consumer advice center, but it should not be more than 400 mg (about four cups of coffee) per day. Pregnant women (including early pregnancy) and breastfeeding women are allowed to drink a small amount of coffee: a daily dose of up to 200 mg caffeine is safe for them, explains the European Food Safety Authority (EFSA).

The right amount of caffeine for children: Drinks containing caffeine are not suitable for children up to the age of three, reports the "Gesund ins Leben" network, an initiative of the Federal Center for Nutrition (BZfE). Older children (3 to 10 years of age) should consume a maximum of 0.2 milligrams of caffeine per kilogram of body weight. The European Food Safety Authority recommends that adolescents (11 to 18 years of age) should not exceed three milligrams per kilogram of body weight. A healthy teenager who weighs 50 kilograms should therefore consume a maximum of 150 milligrams of caffeine per day.

Special case of energy drinks

This means that two cans of energy drinks (one can contains 80 milligrams of caffeine) are too much. The consumer advice center advises children and young people to avoid energy shots, i.e. the higher-dose energy drinks that contain up to 200 milligrams of caffeine per can. Because it can be dangerous if adolescents consume too much caffeine within a few hours. Increased consumption of energy drinks or energy shots can result in headaches, muscle tremors, high blood pressure, shortness of breath, racing heart and circulatory collapse.

Additional alcohol consumption can also increase the risk of cardiovascular problems, because alcohol increases the effect of caffeine, warns the Federal Institute for Risk Assessment (BfR). Almost a quarter of young energy drink consumers consume more caffeine than the recommended maximum amount of caffeine every day from energy drinks alone, according to the Eskimo nutrition study by the Robert Koch Institute in 2019.