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The culprit behind your annoying weight gain could be hiding in your medicine cabinet.
Prescription drugs often come with long lists of side effects, from infections to rashes to suicidal thoughts.
And while it’s well known that some, like steroids, can cause you to gain weight, other commonly prescribed medications, like some painkillers, may come as a surprise.
Pharmacists have revealed to DailyMail.com the commonly taken drugs you never thought were fattening – including some that could add up to five pounds to your waistline in a couple of months.
Pharmacists told DailyMail.com which drugs could be behind your annoying weight gain
Antidepressants
Antidepressants have been blamed for a range of side effects, from insomnia to headaches and even killing patients’ sex lives.
However, some classes of these drugs have also been shown to cause weight gain.
Dr. HaVy Ngo-Hamilton, Clinical Consultant at BuzzRx and pharmacist at the University of Minnesota Medical Center, told DailyMail.com that they are largely tricyclic antidepressants, an older class of drug than the more common selective serotonin reuptake inhibitors (SSRIs).
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“Tricyclic antidepressants, or TCAs, are the class of antidepressants that cause the most weight gain,” she said. “When it comes to weight gain, I try to avoid TCAs as much as possible.”
She noted that TCAs are less frequently prescribed than newer SSRIs because of more severe side effects, including insomnia, bedwetting, and chronic pain conditions such as fibromyalgia.
Some of the most common examples of these include amitriptyline and nortriptyline.
Dr. Ngo-Hamilton estimates that a patient taking these drugs can gain about two pounds per month.
However, he also noted that antidepressants could cause weight gain due to improvements in mood.
A patient may have had little desire to eat, so as the medications regulate their production of serotonin, the happy hormone, they may increase their appetite.
Antipsychotics
Similarly, antipsychotic medications such as clozapine, risperidone, and olanzapine may be prescribed to patients with serious mental health conditions such as schizophrenia and bipolar disorder, as well as some with dementia.
“Antipsychotics slow down our body’s metabolic rate,” Dr. Ngo-Hamilton said.
This is the amount of energy expended at rest. A person with a slower metabolism may burn fewer calories, as the body converts food into energy at a slower rate.
Dr. Ngo-Hamilton noted that these medications can also cause sedation and lethargy, making the patient less likely to exercise or maintain a proper diet. Some of this weight gain could also be due to urinary retention, a known side effect of antipsychotics that causes the kidneys to be unable to properly remove toxins and waste from the urine.
He singled out clozapine (Clozaril) as the most common culprit in this category.
Anticonvulsants
Medications that reduce the frequency of epileptic seizures and nerve pain can also cause weight gain in some patients.
Dr. Ngo-Hamilton specifically pointed to gabapentin, which fights seizures by slowing abnormal signals in the brain, as an example, but other drugs such as pregabalin (Lyrica) and carbamazepine (Tegretol), prescribed to people with spinal injuries, could cause similar effects.
However, “the mechanism by which anticonvulsants cause weight gain is unclear,” Dr. Ngo-Hamilton said.
Recent research has pointed to several theories, including increased appetite, slower metabolism, fluid retention, and disruption of hunger and satiety hormones by the drug.
Dr. Ngo-Hamilton estimates that patients taking these medications may gain about five pounds in the first few months of taking them.
Beta blockers
Beta blockers are medications that lower blood pressure by blocking the effects of the hormone epinephrine, or adrenaline. This helps improve blood flow and slow heart rate.
Dr. Ngo-Hamilton noted that several “older” beta blockers, such as metoprolol, atenolol (Tenormin), and propranolol, have been shown to cause weight gain.
However, like anticonvulsants, the exact mechanism remains unclear. Dr. Ngo-Hamilton noted that one theory is that these drugs slow metabolic rate, similar to antipsychotic drugs.
Additionally, some evidence suggests that because beta blockers lower blood pressure and the amount of blood the heart pumps, patients may become fatigued and have difficulty exercising.
Dr. Ngo-Hamilton estimates a weight gain of two to three pounds in the first six months of taking one of these older beta blockers.
Corticosteroids
Corticosteroids are medications taken to reduce inflammation in the body.
The most common examples are prednisone and dexamethasone, which work by mimicking the effects of the hormone cortisol (which the body releases when stressed or injured) to reduce inflammation.
These are different from anabolic steroids, which increase testosterone levels to enhance athletic performance.
Corticosteroids are usually taken for only a few days at a time, although they may be prescribed long-term for certain problems, such as autoimmune diseases.
“I’m not worried that these drugs might cause weight gain in someone who takes them for a few days. It’s the people who have to take steroids chronically who experience weight gain,” Dr. Ngo-Hamilton said.
She noted that a common side effect is “moon face,” which causes the face to become round, full and puffy. Additionally, mimicking cortisol can also lead to increased appetite.
Dr. Ngo-Hamilton noted that a patient taking steroids for a year could gain up to 10 pounds.
Contraceptive injections
Hormonal contraceptives have long been demonized for causing weight gain, although Dr. Ngo-Hamilton cautions that most contraceptives do not cause weight gain.
“Women who take birth control and experience weight gain are primarily losing water weight,” she explained. “That’s a result of fluctuations in estogren levels.”
However, a birth control method called Depo-Provera (the Depo shot) has been shown to cause weight gain. This is an injection containing the hormone progestin and is given once every three months.
The drug’s label states that nearly 38 percent of women in clinical trials lost more than 10 pounds after using the contraceptive for two years.
In addition, one previous study They found that the drug caused an average weight gain of 20 pounds over 18 months.
Dr. Ngo-Hamilton estimates that most patients would gain between four and five pounds per year.
Statins
About one in five Americans takes statins, which some research suggests may cause weight gain.
About 47 million Americans take statins, a drug intended to lower cholesterol levels, making it one of the most popular medications in the United States.
Statins work by limiting the production of “bad cholesterol” (low-density lipoprotein (LDL)), which can harden and narrow the arteries and increase the risk of cardiovascular disease.
“This can cause a small amount of weight gain, but it’s very rare,” Dr. Ngo-Hamilton said.
A study published in JAMA Internal MedicineFor example, they found that patients taking statins gained between six and 11 pounds compared to those not taking them over a 10-year period.
However, Dr Ngo-Hamilton cautions that much of the evidence is limited and says it’s not worth stopping cheap drugs that lower cholesterol and the risk of diseases like heart disease because of the potential weight gain.
“The benefits definitely outweigh the risk of a small amount of weight gain,” she said.