Common medicines for colds are known to have what effect?

Common medicines for colds often contain ingredients like antihistamines, decongestants, and cough suppressants. Many of these medications can cause drowsiness as a side effect. Antihistamines, in particular, are known for their sedative properties, which can lead to a feeling of sleepiness. This effect is often why some cold medications include warnings about operating heavy machinery or driving while under their influence. Although certain cold medicines may use stimulants to counteract some of these sedative effects, the primary response from the body to many over-the-counter cold remedies tends to be a sense of fatigue or drowsiness. Therefore, the effect of making you sleepy is a common characteristic of many medications designed to treat cold symptoms.