It's not always easy to stop certain medications once you have started them. Abruptly discontinuing some common drugs can lead to worse conditions than before, or even trigger serious withdrawal symptoms, warns a doctor about three common drugs, one of which is taken by millions of people.

Dr. Asif Ahmed, a GP in the U.K., took to Instagram to raise awareness about "disease rebounding," a condition where relapse occurs when certain medications are stopped abruptly.

In a recent video, he highlighted three common medications that are hardest to come off once you start them. He also explained why they need to be tapered off slowly to avoid serious side effects, dependencies, and complications.

"Please don't suddenly stop or change any of your medications if you're on them. There may be a reason why you need them long-term. However, if you're worried about any side effects or rebound withdrawal, please make sure you mention it to your doctor," Dr. Ahmed said in the video.

The first medication on Dr. Ahmed's list is venlafaxine, an SNRI (serotonin-norepinephrine reuptake inhibitor) commonly prescribed as an antidepressant. While it can be highly effective for many, Dr. Ahmed warns that it may cause serious side effects when discontinued abruptly.

"From my experience, it is one of the hardest medications to come off, which is why, despite its effectiveness, it is rarely given as a first-line treatment," he explained in the video.

The next drug Dr. Ahmed warns of is benzodiazepines, a class of medications often prescribed for anxiety, insomnia, and other conditions. While effective in the short term, these medications can lead to dependencies quickly and can have dangerous withdrawal effects when stopped suddenly.

One of the most surprising medications Dr. Ahmed points out is PPIs (proton pump inhibitors), commonly used for acid reflux, such as omeprazole or lansoprazole. Taken by millions, these drugs are widely prescribed, but Dr. Ahmed warns that they are "given far too often," with many people unaware of the rebound symptoms they can cause when stopped abruptly.

"Say you get started on this for your heartburn or your reflux, when you start coming off it your stomach actually reacts by producing more acid which makes the reflux even worse and heartburn worse. This means it's very hard for you to actually come off the medication," Dr. Ahmed said.

"The crazy thing is the rebound is often worse than your initial symptom before you started the PPI. Everyone needs to be told about this before they start the medication," he added.

Read more