Read the Not Mentally Mainstream series.

Having a mental illness sucks. But do you know what sucks more? Having more than one mental illness.

Being diagnosed with two or more mental illnesses (also known as comorbid mental illnesses) is pretty common. This may be because some psychiatric diagnoses share the same pathoetiologic genes, according to the Cross-Disorder Group of the Psychiatric Genomics Consortium. Another reason could be because someone with a mental illness is often attracted to another person with a mental illness. And, well, if they have two different diagnoses and they decide to make babies, their children could be susceptible to both. (Not that I’m blaming your parents or anything!)

One diagnosis that, unfortunately, usually comes with one or two or three more mental illnesses is bipolar disorder. Ninety-five percent of those with bipolar surveyed in the Journal of Affective Disorders met the criteria for at least two other lifetime psychiatric disorders.

Some of the most prevalent comorbid diagnoses with bipolar disorder are:

• Panic disorder
• Obsessive-compulsive disorder
• Substance abuse
• ADHD
• Borderline personality disorder
• Eating disorder

Natasha Tracy, award-winning mental health author, wrote on TalkSpace about how she has bipolar and high anxiety. Because of this, she has a much more complex treatment regimen than if she had a single diagnosis.

"If I take a medication designed to address bipolar depression (a common mood state for me) it’s often what is called 'activating.' In other words, it can give me extra energy. Instead of that being a good thing, this tends to increase my anxiety," she said. "In a mixed state, I experience depression and hypomania symptoms at the same time and then, on top of that, generalized anxiety. This makes me especially tricky to treat."

Sometimes, a person's mental illnesses can be contradictory and counteractive. Sometimes, it's hard to tell where one starts and the other begins.

So what do you do?

Unfortunately, balancing dissimilar treatments involves an extremely tedious and burdensome trial-and-error process, said Mihran Nersesyan, writer for the magazine The Body is Not an Apology.

And Mihran knows firsthand — every member of her immediate family, her partner and her closest friends all have comorbid mental disorders.

"We run the gambit from PTSD to autism, OCD to schizophrenia, addiction to eating disorders, borderline to bipolar, and more," she wrote. "I’ve learned that if you are a person with numerous simultaneous mental disorders, your needs are likely to be different and more intensive than the needs of others. I’m here to tell you one thing: your unique struggles deserve dedicated attention."

For me, I've suffered from both anxiety/panic disorder and depression. According to Psychiatric Times, major depression with subsyndromal anxiety symptoms or unipolar/bipolar depression comorbid with an anxiety disorder are two of the most common comorbidities. About 60 percent of people with anxiety also have depression.

But I'm lucky because, unlike Natasha or Mihran, my two mental illnesses don't co-exist all the time. I think of my anxiety like diabetes or asthma — it's something that, even though I've learned how to treat it, I will always have it. Depression, for me, is more like a fever or strep throat (if a fever and strep throat lasted months and you still had to go to work). Sometimes it'll be years between depressive episodes — but when I get it, it'll be all consuming for about one to six months.

In my experience, I have to treat my anxiety and depression as two separate entities. That's the advice I would give if you suffer from multiple mental illnesses — don't group them together because treatment for one may not work for the other. For me, medication is a godsend when it comes to treating my anxiety but counseling doesn't do anything for me. For depression, it's the opposite. When I'm suffering from depression, counseling is the only thing that can help me through it.

Since I don't have experience with bipolar, borderline personality disorder and more severe mental disorders, I will defer back to Natasha. She said, for people with bipolar, mood stabilization should be achieved before considering any type of antidepressant. That makes sense, especially since some mood stabilizers also have antidepressant effects. According to VeryWellMind.com, mood stabilizers are one of the most important medications for treating bipolar disorder as they control the extreme highs and lows.

Natasha said she recommends medications that both stabilize bipolar and reduce anxiety, such as:

• Valproate
• Antipsychotics
• Gabapentin
• Benzodiazepines (other than alprazolam)

She wrote, "Coping with multiple mental illnesses can seem like an impossible feat. With help from mental health professionals and support from loved ones, however, you can live a full life and work a more peaceful life."