Steve asked
Is it safe to use Benadryl and Robaxin (methocarbamol) together?
Answer
There is considered to be a moderate interaction between Robaxin (methocarbamol) and Benadryl (diphenhydramine) as they have similar side effect profiles. The use of them together is not contraindicated but can cause additive adverse effects and therefore, caution and monitoring are advised.
What Is Robaxin?
Robexin is a muscle relaxant and is indicated for the relief of discomfort of pain that is associated with acute musculoskeletal conditions. The most common side effects of this medication include:
- Dizziness
- Somnolence (feeling of sedation)
- Lightheadedness
- Headaches
The exact mechanism of action of Robaxin isn't well understood but its muscle relaxant effects are most likely due to its central nervous system depressant effects as CNS depression leads to sedation and a reduction in skeletal muscle spasms.
Like other CNS depressants, it is advised that while taking Robaxin, individuals should not engage in physical activities that require both physical and mental alertness until they know how the medication affects them.
What Is Benadryl?
Benadryl is a first-generation antihistamine primarily working as a blocker of histamine at receptor binding sites. Benadryl is a CNS depressant and is well known for its sedative effects, which is why it is a common ingredient in many over the counter nighttime sleep medications, such as Tylenol PM.
The most common side effects of Benadryl include:
- Dry mouth
- Constipation
- Sedation
Taking Benadryl With Robaxin
Taking Benadryl and Robaxin will likely result in additive side effects and their use together should be limited in most situations.
Robaxin has a relatively short half-life and is eliminated from the body quickly. It would be prudent to wait at least 12 hours between Robaxin and Benadryl to avoid additive side effects as much as possible.
