[11] Overdose of sumatriptan can cause sulfhemoglobinemia, a rare condition in which the blood changes from red to green, due to the integration of sulfur into the hemoglobin molecule.

[citation needed] Serious cardiac events, including some that have been fatal, have occurred following the use of sumatriptan injection or tablets.

Sumatriptan's primary therapeutic effect is related in its inhibition of the release of Calcitonin gene-related peptide (CGRP), likely through its 5-HT1D/1B receptor-agonist action.

CGRP is believed to cause sensitization of trigeminal nociceptive neurons, contributing to the pain experienced in migraine.

Oral administration (as succinate salt) has low bioavailability, partly due to presystemic metabolism—some of it gets broken down in the stomach and bloodstream before it reaches the target arteries.

A rapid-release tablet formulation with the same bioavailability but a high concentration can achieve therapeutic effects on average 10–15 minutes earlier than other oral forumulations.

[citation needed] When injected, sumatriptan is faster-acting (usually within 10 minutes), but the effect lasts for a shorter time.

[citation needed] There is no simple, direct relationship between sumatriptan concentration (pharmacokinetics) per se in the blood and its anti-migraine effect (pharmacodynamics).

This paradox has, to some extent, been resolved by comparing the rates of absorption of the various sumatriptan formulations, rather than the absolute amounts of drug that they deliver.

[25] This patch uses low voltage controlled by a pre-programmed microchip to deliver a single dose of sumatriptan through the skin within 30 minutes.

Generic forms of the drug are available in U.S. and European markets after Glaxo's patent protections expired in the respective countries.

[36] According to the American Headache Society, "Patients frequently state that they have difficulty accessing triptans prescribed to them.

"[37] In the U.S. triptans cost from $12 to $120 each, and more than 80% of U.S. health insurance plans place a limit on the amount of pills available to a patient per month, which has been called "arbitrary and unfair.