Can I take losartan every other day 50 mg?

Losartan is a prescription medication and you have to take it as prescribed by your Dr., you should not self medicate. If you have problems with the medication/dosage contact your Dr. for professional medical advice and guidance.
With regards to the side effects a common one of this medication affecting 1% to 10% is insomnia and on the other hand an uncommon side effect is somnolence which affects 0.1% to 1%.
Everyone reacts differently to medications, having said that depending on how you react to the medication you may or may not experience possible side effects if you do and they become bothersome do inform your Dr..
Always contact your Dr. for medical guidance as I mentioned do not self medicate, this is for your own safety.