Viagra makes it real hard for me to come please suggest an alternative.

No, in relation to histamine levels perhaps, if it is low, your libido should drop as well as how fast you climax as well. If the OP claims that it is hard to cum, perhaps he is naturally low or maybe the drug lowers it? I don’t know if the drug is lowering it, so that would be just another angle to find out.

Histapenia (Low Histamine) are over-methylated.

Histadelia (High Histamine) have high whole blood histamine levels and are under-methylated.

Histamine up-regulates the generation of nitric oxide, and nitric oxide down-regulates the release of histamine.