How should I drink water while taking medicine?

Author: Tang Xiange Peking Union Medical College Hospital

Reviewer: Zhao Jie, Chairman of the Chinese Medical Association Clinical Pharmacy Branch, the First Affiliated Hospital of Zhengzhou University, Professor of Pharmacism

Many people take medicine with a glass of water. In fact, some medicines have certain requirements for the amount and temperature of water. For example, if you gulp down a large glass of water after taking syrup, the syrup will be wasted. Some medicines require more water when taken, some medicines require as little water as possible or even no water, and some medicines cannot be taken with hot water. You should know that taking medicines requires certain requirements for water temperature, drinking time, water volume, drinking posture and what kind of water to drink! Only by drinking the right water can the medicine work better.

Drug instructions often say "take with warm water", so what kind of water is considered warm water? The 2020 edition of the Chinese Pharmacopoeia stipulates that water at 70-80℃ is hot water; water at 40-50℃ is warm water; water at 10-30℃ is room temperature water; and water at 2-10℃ is ice water. Therefore, warm water refers to water with a temperature of 40-50℃.

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1. Note that some medicines cannot be taken with hot water!

Some people are impatient and use boiled water to take medicine before it has completely cooled down. However, they do not know that this may destroy the drug ingredients due to the high water temperature! For most drugs, warm water is more suitable, but you should still pay more attention to the following types of drugs. The water temperature should be below 40℃, that is, use cold boiled water to take the drugs.

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2. Which medicines cannot be taken with water immediately?

Some drugs need to work locally in the throat and gastrointestinal tract, so you should not drink a lot of water immediately after taking the drug to dilute the drug, which will cause the local drug concentration to be too low. Some drugs will cause an increase in body fluids after drinking water, so it is not advisable to drink too much water.

The following figure shows the medicines that should temporarily limit water intake after taking them.

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3. How much water should I drink when taking medicine?

Most people are used to taking medicine with just a sip of water, and some even swallow pills dry, but this is actually wrong. Oral medications, especially capsules, can damage the esophageal mucosa and even lacerate the esophageal veins if they adhere to the esophageal wall, causing heavy bleeding with disastrous consequences. In addition to the drugs mentioned in the above picture that limit drinking water, most drugs are excreted through the kidneys after entering the blood. Drinking more water after taking the medicine can help the drug disintegrate and absorb in the gastrointestinal tract, reduce the burden on the kidneys, and promote drug excretion.

The following figure shows the medicines for which it is recommended to drink plenty of water after taking them.

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4. Are there any particular postures for taking medicine and drinking water?

Take bisphosphonates (such as risedronate sodium tablets) for the treatment of osteoporosis as an example. This drug is irritating to the esophagus. If you take the drug in a supine position, the drug cannot be delivered to the stomach as quickly as possible. Some of the drug will adhere to the esophageal wall, causing esophageal damage. You need to be especially careful when taking capsules. The capsule shell is more likely to adhere when it is wet. It is recommended to take the drug while sitting or standing, and walk appropriately.

5. Do not take medicine with the following drinks

Alcohol - except for some drugs that use alcohol as a solvent, alcohol can increase the toxic and side effects of many drugs. Taking alcohol with cephalosporins, niridazole and other drugs together can cause a "disulfiram-like reaction"; taking alcohol with sedatives and sleeping pills together can deepen the depression of the central nervous system, which can be fatal in severe cases.

Fruit juice drinks - The minerals in fruit juice drinks sometimes form insoluble substances with drugs; the acids or alkalis in the juice can neutralize the efficacy of certain drugs or reduce the solubility of drugs; drinks containing grapefruit juice can also inhibit drug metabolism and cause adverse consequences.

Tea - Tea contains a large amount of tannic acid, which can combine with tetracycline drugs (such as minocycline, doxycycline, etc.) and affect the efficacy of the drugs.

Coffee - The caffeine in coffee can cause central nervous system excitement and reduce the efficacy of sedatives and sleeping pills; it can stimulate gastric acid secretion and resist the effects of gastric protective drugs; it can also reduce calcium absorption and weaken the efficacy of anti-osteoporosis drugs.

Milk - Minerals such as calcium and magnesium in milk will form insoluble substances with antibiotics such as quinolones or tetracyclines, thus affecting absorption; the protein in milk can form clots with calcium and aluminum preparations such as calcium lactate, calcium gluconate, and aluminum hydroxide, which not only affects absorption, but also increases the burden on the gastrointestinal tract.

Mineral water - Mineral water is rich in calcium, iron and other ions, which can interact with tetracycline and quinolone antibiotics and affect their efficacy.

If you are unsure about the interaction between medication drinks and drugs, it is recommended that you take medications with warm water and avoid taking medications with alcohol, fruit juice drinks, coffee, milk, or tea.