Can carbamazepine (Tegretol) cause sexual dysfunction?

Can Tegretol (Carbamazepine) Cause Sexual Dysfunction?

Yes, carbamazepine (Tegretol) is definitively associated with sexual dysfunction in men, including erectile dysfunction, decreased libido, and reduced sexual frequency, primarily through hormonal mechanisms that lower bioactive testosterone levels. 1, 2, 3

Mechanism of Sexual Dysfunction

Carbamazepine causes sexual problems through a well-established hormonal pathway 2, 4:

• Induces hepatic cytochrome P450 enzymes, which accelerates the metabolism of sex steroids and increases production of sex hormone-binding globulin (SHBG) 2, 4
• Decreases free androgen index (FAI) and bioactive testosterone levels, which directly impairs sexual function 5
• These hormonal changes correlate with the duration of carbamazepine therapy—the longer you take it, the worse the effect 5

Clinical Evidence of Sexual Impact

The magnitude of sexual dysfunction with carbamazepine is substantial 3:

• Erectile dysfunction: Men taking carbamazepine have 17.33 times higher odds of having erectile dysfunction compared to controls 3
• Reduced sexual frequency: 10.47 times higher odds of having sexual intercourse less than 3 times per week 3
• Overall prevalence: 40-70% of male epilepsy patients experience sexual problems compared to only 10% of healthy men 2

FDA-Labeled Adverse Effects

The FDA drug label for carbamazepine explicitly lists sexual side effects 1:

• Impotence is documented as a genitourinary adverse effect 1
• Impaired male fertility and/or abnormal spermatogenesis have been reported 1
• Animal studies showed testicular atrophy and aspermatogenesis at therapeutic-range doses 1

Semen Quality Impact

Beyond erectile function, carbamazepine significantly impairs reproductive parameters 3:

• Sperm morphology: 93.7% of carbamazepine users had abnormal morphology (<14%) versus 34.6% of controls 3
• Sperm motility: 98.4% had reduced A+B motility (≤50%) versus 85.4% of controls 3
• Sperm vitality: Altered in 27% of epileptic subjects versus 5.4% of controls 3

Management Strategy

When sexual dysfunction occurs with carbamazepine, follow this algorithm 2, 4:

1. First-line intervention: Switch to a non-enzyme-inducing antiepileptic drug 2, 4

   • Oxcarbazepine is the best-studied alternative—metabolic and endocrine alterations can normalize after switching from carbamazepine, and carbamazepine-induced impotency can be cured 2
   • Lamotrigine also shows benefit for sexual dysfunction without hormonal effects 2, 4
   • Levetiracetam or gabapentin are additional options for partial epilepsy 4

2. If medication change is insufficient or not possible 2:

   • Consider testosterone replacement therapy, which may improve both sexual function and reduce seizure frequency 2
   • Bromocriptine may be required if prolactin elevation is present 2

3. For erectile dysfunction specifically 2:

   • Sildenafil (Viagra) can successfully treat erectile dysfunction independent of the underlying cause 2

Critical Clinical Pitfall

Do not assume sexual dysfunction is purely psychological or related to epilepsy itself—the medication is often the primary culprit through measurable hormonal changes 2, 4. The hormonal alterations are dose-dependent and duration-dependent, meaning they worsen over time with continued carbamazepine use 5.

Additional Context

While epilepsy itself can contribute to sexual dysfunction through effects on the amygdala and temporal lobe structures 6, the enzyme-inducing properties of carbamazepine represent a modifiable and reversible cause that should be addressed first 2, 4.